JPEGs and File Size

GordonBGood

Further to our previous discussion I would be very grateful to know whether the slightly darker images I mentioned would be a logical outcome of saving edited images which are more highly compressed than recommended?
Are you able to advise?
David

dchass said:

GordonBGood
Further to our previous discussion I would be very grateful to know
whether the slightly darker images I mentioned would be a logical
outcome of saving edited images which are more highly compressed
than recommended?
Are you able to advise?

Click to expand...

dchass said:

And including the text from your last post in the previous thread:

Click to expand...

dchass said:

Thank you again for your detailed explanations. Much of it is a little > detailed for my comprehension. Nevertheless, I think the summary is:

Click to expand...

dchass said:

• for good quality PSE3 edited 10" x 8" prints, save at 1.8-2.0Mb file size.
• for good quality PSE3 edited 6" x 4" prints, save at 400-500Kb file size.

Click to expand...

dchass said:

I have previously tried some 10" x 8" test prints (with considerable fine detail) from files of 450-900Kb and to me they turned out v crisply, but perhaps a little dark compared to viewing on my 21" Dell LCD screen(1600 x 1200 screen res). Would this be a logical outcome of saving images which are more highly compressed than recommended?

Click to expand...

First, by fine detail I mean FINE DETAIL where the individual features are of very high contrast (meaning that the adjacent high and low colour levels are separated by perhaps a 100 out of 256 possible levels in a JPEG, which has 256 levels per RGB colour channel) and these FINE DETAILS are no more than a two or three pixels across each. Examples of this are garden/forest scenes (tiny leaves), lawn grass, animal fur, or people hair. You look for artifacts by looking at flat textured areas such as sky, paper, or unpatterned cloth that is right next to the FINE DETAIL, looking for a artificial speckled pattern that intrudes by up to about 8 to 16 pixels into the flat patterned areas.

IMHO, no, the darkness in your prints has nothing to do with the JPEG size; it is more likely to do with the viewing conditions for your prints and your montor and the gamma tone response of each. As usual (;-) your question is incomplete in that you don't say how you made the prints, your own inkjet printer or a commercial service. It is difficult to compare prints and the monitor screen side-by-side, as ideally you view a monitor in near dark viewing environments with a relative gamma curve that has been adjusted so that the actual monitor gamma is higher by about 10 to 15% than that used for viewing in bright conditions. On the other hand, a print is best viewed under bright lights as they are usually printed to a specification that assumes about 200 Lux illumination; this is important because what you see in a print is reflected back to you from the light source, which ideally should have the same white balance colour temperature as the white balance colour temperature to which your monitor is adjusted. Those that view both types of images side-by-side usually use the dark environment and a spot light for print viewing, although you still then must allow a couple of minutes when switching views to let your eyes adjust to the different illumination levels.

In my experience I find that high quality LCD monitors, as I understand large Dell LCD monitors such as yours to be, have a lower natural gamma tone response than CRT monitor or sRGB images, making images too bright when viewed if no gamma correction is applied. If the monitor is of high enough quality, you will be able to use Norman Koren's gamma chart available from:

http://www.normankoren.com/makingfineprints1A.html#gammachart

and another from Hans Brettel at:

http://www.tsi.enst.fr/~brettel/TESTS/Gamma/Gamma.html

to estimate your monitor's average gamma. Note that the first of these links doesn't produce accurate results if your monitor has a true sRGB setting in its On Screen Menu Display, where the second still does. For viewing sRGB (or Adobe RGB) images in bright surroundings you should set your average gamma to 2.2, but for viewing in recommended dim viewing conditions (as assumed by these standards to minimize glare, flare, and reflections), you should set an average gamma of 2.5 or higher. In addition, for viewing sRGB images without colour management in your viewer, you need to adjust the monitor tone response curve so it brightens the shadow details (below about 64 out of 256 levels) by up to about 5% at about level 16, with zero still zero, in order to compensate for the shape of the sRGB tone curve, which is not a pure gamma power function.

The above may be difficult for you to understand, but for a start try to check your monitor's gamma and tell me what you are using for a computer and video card and I may be able to help further.

A further problem if you are using an inkjet printer is that, in my experience, many of the drivers for those printers use colour management settings that leave the gamma too high and thus the midtones too dark; much of this may be due to using paper other than the manufacturer's paper, with a different paper absorbsion and consequent dot spread of the black ink into the other colours. If this is your problem, you need a proper colour profile for your printer (and access to a scanner to develop one yourself, or you need to purchase one), and software with colour management turned on to use it (and a bit of knowledge on how to make all the bits work together). Some good software for this is Mike Chaney's Profile Prism for profiling and QImage for printing, both available from http://www.ddisoftware.com . Although I have used this software with excellent results, I now just use QImage to prepare images for my local Fuji print service using Fuji Frontier printers and paper, as I can't be bothered maintaining the print system for the few large prints I do. Perhaps this would be your best option, too, especially if your knowledge is a bit weak in these areas.

Hope this helps, GordonBGood

Gordon
An extremely helpful response.

You seem to have touched exactly on some of the areas that have been of interest to me. You are right... my knowledge is a bit weak in these areas, but I will study your links over the next few days and get back in touch.
Many thanks
David

GordonBGood said:

The above may be difficult for you to understand, but for a start
try to check your monitor's gamma and tell me what you are using
for a computer and video card and I may be able to help further.

Click to expand...

My computer is an AMD 1800XP with 64Mb video NVIDIA GeForce2 MX/MX 400, with Dell 20" screen at res of 1600x1200.
Adobe gamma in Control Panel setting shows 2.2 as default.

Have had a look at the Norman Koren and Hans Brettel links but have not adjusted anything as yet. The Hans Brettel reading on opening showed Gamma = 2.54 with grayval background at 128 and grayval bright lines at 168. (Not sure how to best adjust these).

Reply below:

Everything should be done as an Administrator if you have more than one user account, and you should be sure you have set Display Properties to use at least 24 bit colour.

dchass said:

My computer is an AMD 1800XP with 64Mb video NVIDIA GeForce2 MX/MX
400, with Dell 20" screen at res of 1600x1200.
Adobe gamma in Control Panel setting shows 2.2 as default.

Click to expand...

You can't tell too much from Adobe Gamma as to gamma calibration, as it is too coarse to use to adjust the gamma, which is why I recommend other methods. I recommend that you disable it by removing the Adobe Gamma Loader link from Start/All Programs/Startup folder. You can always restore the link later if you save it or create it to the loader in its usual location in C:\Program Files\Common\Adobe\Calibration.

dchass said:

Have had a look at the Norman Koren and Hans Brettel links but have
not adjusted anything as yet. The Hans Brettel reading on opening
showed Gamma = 2.54 with grayval background at 128 and grayval
bright lines at 168. (Not sure how to best adjust these).

Click to expand...

First, set your monitor to sRGB if it has such a setting under Colors in the monitor menu. This should set your color balance to D65, the contrast and brightness to the best black point possible, and the tone response curve to that of sRGB so that using no monitor colour profile will cause Windows to default to the sRGB colour profile that should match the response of your monitor quite closely. If you don't have such a setting, set the white balance to D65 or 6500K (essencially the same thing) using your monitor's menu, if it has such a setting. If it doesn't, you'll have to guess at it using the colour adjustment part of the monitor menu and comparing the warmth/coolness of the white on your monitor with a monitor that has such a setting.

If you don't have a sRGB setting, you should now reset any contrast/brightness adjustments you may have made to factory default by using the reset function in the monitor menu. At this point you should be able to see all the differences in the grey bar at the bottom of the reviews on the dpreview site. If you can't see all of the blocks at the black end when viewing the monitor in the dark, it is because your monitor has too low a contrast ratio and too high of a gamma tone response or because the default settings for contrast/brightness are wrong. Be careful adjusting these on an LCD monitor, as they can affect the proper response of the monitor if too extreme changes are made.

Now use the Norman Koren chart to determine at what gamma level on the chart the bar looks about the same across, or about half way between where the middle bar looks white to where it looks dark when viewed from staight on, as per his explanation. Note that this chart doesn't work very well when you have a sRGB setting on your monitor menu. Also, if you can't make out anywhere where it looks about the same across and this changes depending on the angle you view the monitor, your monitor can't be calibrated by software.

To use the Brettel chart, leave the top reading at 128 and adjust the bottom one until the inner box looks about the same as the top one when you stand back and squint (viewing it perpendicularly to the screen surface). The value you get is your average gamma in the midtones. All of this is best done in the dark or near dark to avoid reflections and glare.

I prefer this type of chart. For a modern CRT monitor when the black level is adjusted properly (usually with contrast to maximum and adjusting only the brightness control), one almost always gets a native gamma of about 2.5 using the Brettel chart. In my experience, you will usually get a lower gamma level for LCD monitors of something like 1.8 to 2.0. Some monitors have a gamma adjustment in the monitor menu, which may allow you to adjust the "native" gamma. If you have this, I prefer adjusting it to as close to 2.5 as possible for viewing in dark conditions (recommended).

Right click your Desktop area and select Properties. Click Advanced at the bottom right and choose the Color Management Tab. I recommend that you remove any (probably manufacterer supplied) monitor colour profiles from the colour managment setting as they are usually wrong. This will cause Windows to default to a sRGB profile for your monitor.

Now choose the nVidia tab and select colour correction on the left side, which should give you a page with a gamma adjustment setting. The simplest thing you can do is dial in a relative gamma correction so that the Brettel chart shows you now have your desired gamma, whether it be 2.2 for viewing in very bright conditions, 2.5 for viewing in moderately dim conditions (recommended, as that is the basis of the sRGB standard), or 2.7 or 2.8 for viewing in almost pitch dark. The only problem with this is that this simple gamma curve doesn't match the sRGB one in the shadow detail. There are two solutions:

1) Use Adobe Gamma from the control panel to build a new colour profile that is based on sRGB with a simple 2.2 gamma curve. You won't be using the gamma calibration sliders part of this because we disabled the gamma loader program (remember?), and will be leaving the monitor phosphor and white point to the sRGB default values. Name this profile as per your Dell model number. You will note that you use a simple 2.2 curve and not the actual gamma setting of your monitor because we want your monitor to have darker midtones when viewing in darker conditions in order to give your eyes a better (more accurate) impression of contrast. This solution works when viewing your images with a colour managed viewer with colour management turned on, such as PhotoShop, QImage, Paint Shop Pro 8 and greater, etc., but not with Internet Explorer, ACDC, or the built in Windows viewer, etc.
Next post, how to adjust so this works both with and w/o colour management.

GordonBGood

GordonBGood said:

Reply below:

Everything should be done as an Administrator if you have more than
one user account, and you should be sure you have set Display
Properties to use at least 24 bit colour.

The only problem with this setting a simple power gamma function curve
is that this simple gamma curve doesn't match the sRGB one in the
shadow details. There are two solutions:

1) Use Adobe Gamma from the control panel to build a new colour
profile that is based on sRGB with a simple 2.2 gamma curve as explained
in the last post. However, shadow details in true sRGB images will be too
dark unless you view your images with a fully colour managed
viewer with colour management turned on, such as PhotoShop, QImage,
Paint Shop Pro 8 and greater, etc., but not with Internet Explorer,
ACDC, or the built in Windows viewer, etc., which do not have this.

Click to expand...

2) In order to view true sRGB images correctly both with and without colour management, DO NOT CREATE the profile as from part one and let Windows use the default sRGB one for when there is none specified in the Display Properties/Color Management tab. Then make your calibration match the complex sRGB tone response curve so that you boost the brightness in the shadow details by altering the shape of the simple relative gamma correction you used to get your target monitor gamma. Change the drop down under Color Profile: to Advanced Mode and add some points to the curve in the chart above so that you have a point at 0.02 in which is about 0.03 higher than it would nomally be on the simple curve, at 0.06 in it is also 0.03 higher, at 0.20 input it's 0.01 higher, and at 0.39 put a point on the curve that is at the same output as it would normally be to fix the correction back to normal for all values higher than this. This correction will make your monitor response approximate that of the sRGB colour profile and intent such that you won't be able to see the difference by eye. A harware solution such as Colorvision/Pantone's ColorCal will build a somewhat more accurate model in some respects, but you likely wouldn't see the difference between two monitors calibrated by my method above and theirs given that the target gammas and tone response curves are the same and you can do a reasonably job of setting D65 white balance.

This works because almost all modern monitors have very close the the colour gamut of sRGB so that full colour gamut calibration is unnecessary, and the human visual system self adjusts for quite large changes in white balance. As for gamma, as you can see, we prefer different total system gamma within a range depending on the ambient environment light levels.

Regards, GordonBGood

IMO it is also worth to look at http://www.aim-dtp.net

Greetings,
Bogdan
--
My pictures are my memories
http://freeweb.siol.net/hrastni3/

GordonBGood said:

You can't tell too much from Adobe Gamma as to gamma calibration,
as it is too coarse to use to adjust the gamma, which is why I
recommend other methods. I recommend that you disable it by
removing the Adobe Gamma Loader link from Start/All
Programs/Startup folder. You can always restore the link later if
you save it or create it to the loader in its usual location in
C:\Program Files\Common\Adobe\Calibration.

Click to expand...

I am most grateful for your v detailed instructions, and have started working my way thru them. Have not advanced past Adobe Gamma Loader yet because pressing Start/Pgms/Adobe Gamma Loader does not produce any result. Right clicking Adobe Gamma Loader then pressing Delete only removes the shortcut. Is there a vital step I am missing?
Many thanks
David

I abandoned Adobe Gamma last year and have been using QuickGamma (based on Norman Koren's site) with better and more consistent results. I use a crt so don't know how well QuickGamma works with lcd's.

Here's the web site to download (free) QuickGamma:
http://quickgamma.de/indexen.html

A good explanation and instructions for QuickGamma is found here:
http://quickgamma.de/infoen.html

Be sure to delete Adobe Gamma from the startup folder or you'll be trying to double calibrate, which causes a calibration nightmare!

Tom

dchass said:

GordonBGood said:

You can't tell too much from Adobe Gamma as to gamma calibration,
as it is too coarse to use to adjust the gamma, which is why I
recommend other methods. I recommend that you disable it by
removing the Adobe Gamma Loader link from Start/All
Programs/Startup folder. You can always restore the link later if
you save it or create it to the loader in its usual location in
C:\Program Files\Common\Adobe\Calibration.

Click to expand...

I am most grateful for your v detailed instructions, and have
started working my way thru them. Have not advanced past Adobe
Gamma Loader yet because pressing Start/Pgms/Adobe Gamma Loader
does not produce any result. Right clicking Adobe Gamma Loader then
pressing Delete only removes the shortcut. Is there a vital step I
am missing?

Click to expand...

David, when you click on Adobe Gamma Loader you won't see any change for two reasons:

1) Any gamma corrections it may have applied have already been loaded when you logged on to your user account, so a extra load doesn't do anything. If you want to see it do something, mess with the gamma setting using the Display Properties as I explained in my previous posts so you have a visible difference, then click on the Adobe Gamma Loader, and you may see it revert. This is dependent on it finding a gamma correction in an Adobe Gamma produced colour profile to apply, though. So

2) You have to have produced a Adobe Gamma Loader compatible colour profile for your monitor, which then will include the gamma calibration Look Up Table (LUT)

Removing the shortcut is what you want to do, as that will then make the loader not run when you log in/start up your user account, thus it will not override any settings you make using the Display Properties. Or conflict with any other applications such as QuickGamma than you may care to use. As I explained, if you really want to run the loader again later without re-installing PS/Elements, just save the shortcut (ie. copy it somewhere) before deleting, or it can be re-created as a new shortcut to where the loader executable file really lives.

Regards, GordonBGood

hbx2004 said:

IMO it is also worth to look at http://www.aim-dtp.net

Click to expand...

Bogdan, it is a useful site in some respects but there has been a lot of controversy about some of his claims. The things that are good about his site are:

1) His technique for checking black point setting as per the link below without using a special test pattern is useful, except it probably won't work for LCD monitors, whose contrast and brightness controls generally work differently:

http://www.aim-dtp.net/aim/calibration/blackpoint/crt_brightness_and_contrast.htm

2) His technique for setting white balance isn't bad, especially if your monitor doesn't have an exact white balance setting point as per D65 or 6500K as per:

http://www.aim-dtp.net/aim/photoshop/v5/ps5_rgb_calibration.htm#white-point

Notes are that his "noon sunlight" used for setting isn't exact everywhere in the world, is dependent on how overcast the sky is, and is rarely as cool as 6500K, averaging more like 5500K to 6000K for non-overcast conditions. White point setting isn't that critical anyway, as the human visual system does it's own compensations with this type of error range.

3) His techniques for setting monitor gamma aren't bad, but his recommendation of using a monitor setting of Gamma 1.0 to 1.25 IS ABOLUTELY AND UNEQUIVOCALLY WRONG and is where the controversy comes in. Timo is correct that your editing workspace ideally has 16 bits per channel and gamma 1.0 so that unintented hue shifts don't occur for major editting operations, but YOU CAN NOT VIEW IMAGES CORRECTLY ON A MONITOR WITH A REAL GAMMA SETTING OF 1.0 to 1.25, as even if your images were all converted to be based on that, you can then only view a dynamic range of 256:1 or 8 f-stops on the usual monitor colour depth of eight bits per channel. Note that the gamma value shown under Display Properties is 1.0 because this is relative gamma as applied to the native gamma (2.5 for CRT monitors; usually 1.8 to 2.0 for LCD monitors). There is no need to set your monitor gamma to 1.0 in order to use a workspace with a gamma of 1.0 (must be 16 bits per channel in order not to lose dynamic range), as modern editors such as PhotoShop will automatically do the conversion to view that workspace properly on a properly adjusted monitor colour space. That said, Timo's gamma setting charts such as the one for my recommended setting of gamma 2.5 (for viewing in moderately dim conditions) isn't bad, if overly complex since almost all monitors reasonably closely follow the ideal power curve. Chart at:



His comments about changing the individual gamma settings for RGB aren't really pertinent to modern CRT monitors and are likely only pertinent to LCD monitors when the brightness/contrast controls are adjusted to cause the tone response to be distorted, which can also cause the tone response to not follow an ideal power function.

4) His comments about phosphors show that he has never used a hardware calibration device. He is correct that most modern monitors use Trinitron or P22 type phosphors and that these are reasonably close to each other, but what he fails to note is that almost all information about phosphor chromaticities from manufacturers sites is wrong, and that most monitors phosphors are best modelled by the HDTV standard that is embedded in the sRGB standard, which is very close to the P22 phosphor average chromaticities and reasonably close to average Trinitron chromaticies (although Trinitron is the commonly used spec that is the furthest away from the rest).

This information has been discredited, not because some of the information and techniques aren't good, but because blind application of all of the information by people who don't understand the concepts will produce a very hard to use system.

Regards, GordonBGood

Tom, QuickGamma is an excellent little application which I highly recommend with the following limitations:

1) The Norman Koren calibration chart doesn't work very well with non pure power curve tone response monitors, such as LCD monitors that have a distorted response due to extreme brightness/contrast control changes, nor is it accurate for monitors that have a sRGB setting, which setting changes the tone response so that it does not have the pure power function shape in the shadow detail. I prefer the type of calibration box as used in the Hans Brettel link I provided earlier or the charts at:

http://en.wikipedia.org/wiki/Gamma_correction

which allow you to bracket your estimation of monitor gamma by looking at where the calibration square err on the side of too bright to too dark and choosing a point halfway between.

2) The application does not have a check box so that you can have the resultant calibration reflect the shape of the sRGB tone response, which is not a pure gamma power function as set by this program. This technique is what I am trying to teach in my last post yesterday.

3) A limitation of all such programs including those that apply the calibration results from hardware calibration devices such as Colorvision products or Eye One is that MS Windows allow only one calibration setting per video adapter even though there may be more than one monitor connected to it. Adjusting Display Properties as I suggest modifies the calibration through the display driver and allows one to apply different settings to each monitor.

As to your last paragraph related to "double calibration", while one must disable gamma loader programs that are run from the Startup folder, it is for the reason that one does not want these settings to override the ones applied by GuickGamma (or by the Display Property settings, as I suggest). Double calibration is not possible as these programs do not apply corrections additively but replace the values in the LUT with their own version.

QuickGamma produces good results when used with colour managed viewers, but leaves true sRGB images dark in the shadow details when images are viewed without colour management as with most Internet browsers. It also assumes that you would want to adjust your gamma to 2.2, which the sRGB standards people recommend only for viewing in bright office type conditions. For viewing in more ideal dim to dark conditions, they recommend more something like the native 2.5 gamma that almost all modern CRT monitors have when black point is set correctly.

Since I am using CRT monitors, I don't use QuickGamma, as I leave them set to their native gamma 2.5 for viewing in dim environments. I then apply a slight increase in shadow detail brightness using Display Properties as explained in the last of yesterday's posts.

I find the various gamma calibration charts useful in a different way than the usual use: I set them to the assumed native gamma response of my monitors of gamma 2.5 and then adjust black point using contrast = 100% and brightness as appropriate to get a gamma value of 2.5 as per the chart. I find that the brightness setting obtained this way almost always confirms that obtained using other accurate techniques. This confirms that my CRT monitors have a native gamma of 2.5.

Regards, GordonBGood

Tom Ketcham said:

I abandoned Adobe Gamma last year and have been using QuickGamma
(based on Norman Koren's site) with better and more consistent
results. I use a crt so don't know how well QuickGamma works with
lcd's.

Here's the web site to download (free) QuickGamma:
http://quickgamma.de/indexen.html

A good explanation and instructions for QuickGamma is found here:
http://quickgamma.de/infoen.html

Be sure to delete Adobe Gamma from the startup folder or you'll be
trying to double calibrate, which causes a calibration nightmare!

Click to expand...

Gordon, thank you for the information and clarification. I mistakenly thought Adobe Gamma created a monitor profile that worked with the LUT values to adjust RGB values but didn't actually change the LUT.

The web site you referenced is informative; I hadn't seen that site before.

I use QuickGamma to set individual RGB values depending on the lighting conditions I'm using to edit images. When editing for printing, I adjust for dim lighting using a full-spectrum flourescent bulb. (One of these days I may spend the money for a good lamp and even a monitor calibration and profiling system.) I'm fortunate in that my monitor seems to behave pretty well and I get a good (not perfect) match when printing using custom printer profiles. I'm coming to the realization though, that you have to set your monitor for the specific lighting conditions that the prints will be viewed under. Hence the value of having custom monitor profiles.

I'm going to try your suggestion of using gamma 2.5 to see how it affects both print output and web image viewing.

Thanks again. Tom

Thankyou Gordon. A v complicated set of instructions to follow, let alone for you to have described in precise detail.

GordonBGood said:

First, set your monitor to sRGB

Click to expand...

Done, set to sRGB Colour Space Profile.

GordonBGood said:

At this
point you should be able to see all the differences in the grey bar
at the bottom of the reviews on the dpreview site. If you can't
see all of the blocks at the black end when viewing the monitor in
the dark, it is because your monitor has too low a contrast ratio
and too high of a gamma tone response or because the default
settings for contrast/brightness are wrong.

Click to expand...

OK, done.

GordonBGood said:

In my
experience, you will usually get a lower gamma level for LCD
monitors of something like 1.8 to 2.0.

Click to expand...

Done, best reading was 1.96.

GordonBGood said:

Some monitors have a gamma
adjustment in the monitor menu, which may allow you to adjust the
"native" gamma. If you have this, I prefer adjusting it to as
close to 2.5 as possible for viewing in dark conditions
(recommended).

Click to expand...

Have not tried this.

GordonBGood said:

Now choose the nVidia tab and select colour correction on the left
side, which should give you a page with a gamma adjustment setting.

Click to expand...

This path was difficult. Found it under NVIDIA/Additional Properties/TwinView/Device Settings/Colour Correction/Gamma.

GordonBGood said:

The simplest thing you can do is dial in a relative gamma
correction so that the Brettel chart shows you now have your
desired gamma, whether it be 2.2 for viewing in very bright
conditions, 2.5 for viewing in moderately dim conditions
(recommended, as that is the basis of the sRGB standard),

Click to expand...

1.0 is the default. 2.5 gives a v light/pale screen, so left it at 1.0.

GordonBGood said:

1) Use Adobe Gamma from the control panel to build a new colour
profile that is based on sRGB with a simple 2.2 gamma curve. You
won't be using the gamma calibration sliders part of this because
we disabled the gamma loader program (remember?), and will be
leaving the monitor phosphor and white point to the sRGB default
values. Name this profile as per your Dell model number. You will
note that you use a simple 2.2 curve

Click to expand...

Got lost here as I could not see any simple 2.2 curve.
Regards
David

We're getting closer!!! Further comments below:

dchass said:

GordonBGood said:

First, set your monitor to sRGB

Click to expand...

Done, set to sRGB Colour Space Profile.

Click to expand...

Was this done using the monitor menu controls or the Display Properties? If done using the monitor menu, than you shouldn't have to use method 2 at the bottom; if done using Display Properties, you should use method 2 in order to properly view true sRGB images without colour management such an in Internet Explorer so that shadow details are as bright as intended.

dchass said:

dchass said:

At this
point you should be able to see all the differences in the grey bar
at the bottom of the reviews on the dpreview site. If you can't
see all of the blocks at the black end when viewing the monitor in
the dark, it is because your monitor has too low a contrast ratio
and too high of a gamma tone response or because the default
settings for contrast/brightness are wrong.

Click to expand...

OK, done.

dchass said:

In my
experience, you will usually get a lower gamma level for LCD
monitors of something like 1.8 to 2.0.

Click to expand...

Done, best reading was 1.96.

dchass said:

Some monitors have a gamma
adjustment in the monitor menu, which may allow you to adjust the
"native" gamma. If you have this, I prefer adjusting it to as
close to 2.5 as possible for viewing in dark conditions
(recommended).

Click to expand...

Have not tried this.

dchass said:

Now choose the nVidia tab and select colour correction on the left
side, which should give you a page with a gamma adjustment setting.

Click to expand...

This path was difficult. Found it under NVIDIA/Additional
Properties/TwinView/Device Settings/Colour Correction/Gamma.

dchass said:

The simplest thing you can do is dial in a relative gamma
correction so that the Brettel chart shows you now have your
desired gamma, whether it be 2.2 for viewing in very bright
conditions, 2.5 for viewing in moderately dim conditions
(recommended, as that is the basis of the sRGB standard),

Click to expand...

1.0 is the default. 2.5 gives a v light/pale screen, so left it at
1.0.

Click to expand...

No, this is the relative gamma to which I referred. Since I recommend a final monitor gamma of 2.5 and your current monitor gamma appears to be 1.96, you need to apply a relative gamma correction of 1.96/2.5 = 0.784 or about 0.78 for viewing in fairly dim environments (recommended), or 1.96/2.2 = 0.89 for viewing in bright conditions. If your monitor has a monitor menu setting to sRGB, this should be all you need to do. If it does not, than you should perform method two at the bottom of this post.

dchass said:

dchass said:

1) Use Adobe Gamma from the control panel to build a new colour
profile that is based on sRGB with a simple 2.2 gamma curve. You
won't be using the gamma calibration sliders part of this because
we disabled the gamma loader program (remember?), and will be
leaving the monitor phosphor and white point to the sRGB default
values. Name this profile as per your Dell model number. You will
note that you use a simple 2.2 curve

Click to expand...

Got lost here as I could not see any simple 2.2 curve.

Click to expand...

Remember that this is method 1 that only works ideally when used with a colour managed viewer. I recommend method 2 from the follow on post that does not require that you use Adobe Gamma at all. However, for those that opt for method 1, when you use Adobe Gamma and base the source profile on the sRGB profile, Adobe Gamma will generate a simple 2.2 gamma when the gamma drop down box has 2.2 selected.

For method 2, on the Gamma page that you have found change the drop down selector below the words "Color profile:" to Advanced, then add four points on the curve by clicking on it. These points should have the following co-ordinates when using the 0.78 relative correction to give you an overall 2.5 monitor gamma:

in out
1) 0.02 0.04
2) 0.06 0.06
3) 0.20 0.14
4) 0.39 0.30

leaving the end points at (0.0, 0.0) and (1.0, 1.0). Note that other relative gamma requirements will have different values for these co-ordinates. Apply and ok all these settings and you are at the end of method 2 (if it was necessary).

You should have now have a monitor that is calibrated to close to the sRGB spec, including recommended viewing conditions, allowing you to correctly view true sRGB images both with and without colour management (in a dim viewing environment).

Regards, GordonBGood

Tom, glad to help. Other comments as follows:

Tom Ketcham said:

Gordon, thank you for the information and clarification. I
mistakenly thought Adobe Gamma created a monitor profile that
worked with the LUT values to adjust RGB values but didn't actually
change the LUT.

Click to expand...

Adobe Gamma does two things as follows:

1) Creates a monitor colour profile as per the parameters you specify based on the profile you load as a starting point and installs the generated profile as the name you specify as your default monitors default colour profile. The paramenters specified are white balance, phosphor chromaticities, and expected image tone response curve, with the TRC being limited to simple gamma power curves, which approximate the base colour profile's TRC's if they are other than the standard curves.

2) Allows one to calibrate the monitor white point and TRC's using the LUT so as to match the above profile. The LUT values are embedding in the above generated profile, but are only used by Adobe Gamma Loader (or an equivalent program), normally by running on user startup or log on. However, it has many limitations including the following:

a) One can't input numeric values for the gamma adjustments, the adjustments tend to be too coarse, and the horizontal lines on the adjustment chart are too coarse to easily do any accurate adjustment.

b) It calibrates exactly to the specified simple gamma curve in 1) and doesn't allow one to calibrate for viewing in dimmer viewing environments.

c) Since it calibrates to a simple gamma curve (as QuickGamma does), true sRGB images won't be correctly viewed with a non colour managed viewer application, as shadow details will be left too dark.

d) Although it has the provision to adapt a monitor to a different white point than may be offered by the monitor (ie. D65 or D50 when the monitor only offers D93), the calculation is done incorrectly and the resulting white balance is wrong.

Tom Ketcham said:

I use QuickGamma to set individual RGB values depending on the
lighting conditions I'm using to edit images. When editing for
printing, I adjust for dim lighting using a full-spectrum
flourescent bulb. (One of these days I may spend the money for a
good lamp and even a monitor calibration and profiling system.)

Click to expand...

A good spot lamp so that you can view your prints under the right illumination without putting glare on your monitor would be worthwhile if you do a lot of work with prints. But the best Digital Darkroom work is done with a very dark environment and the gamma 2.5 or more (on average) I mentioned as far as the monitor is concerned. Any spot lamp should NOT illuminate the monitor. In my experience, for CRT's a monitor calibration and profiling system is hardly worth the money if you use the techniques I've outlined here. Some LCD's monitors are more variable as to TRC and often don't have exact white balance settings, so these systems are of somewhat more use with such monitors.

The trouble with using QuickGamma to adjust the RGB gamma values separately is that you are affecting the white balance of the midtones without changing the white balance at the endpoints. I find that with almost all modern CRT monitors the RGB channels are a very close match to each other and that one does not need to/should not adjust the channels separately. If one needs to adjust white balance, it is better done through the RGB gain/custom white balance controls from in the monitor's menu.

Tom Ketcham said:

I'm fortunate in that my monitor seems to behave pretty well and I
get a good (not perfect) match when printing using custom printer
profiles. I'm coming to the realization though, that you have to
set your monitor for the specific lighting conditions that the
prints will be viewed under. Hence the value of having custom
monitor profiles.

Click to expand...

Or view the prints under the illumination they were intended for. Most print colour spaces are intended to be illuminated by D50 or about 5000K light (unless you generate custom print profiles that change this), where as monitor viewing spaces are generally at D65 or 6500K. One can set the monitor to D50, either if it has such a setting or by manipulating the individual RGB channel gains in Custom Colour Balance (or some such name), but then your monitor will appear quite warm in white balance for general use and the normal monitor profiles (such as sRGB and Adobe RGB) will be incorrect as they specify D65.

Tom Ketcham said:

I'm going to try your suggestion of using gamma 2.5 to see how it
affects both print output and web image viewing.

Click to expand...

Remember it is intended for viewing in dim environments and that thus it will make your midtones darker than at your normal gamma 2.2. The reason that this is good when viewed in darker conditions is the our pupils open up in lower ambient light to see the resulting lower contrast in the shadow details as being more representative of the scene as shot.

Regards, GordonBGood

Thankyou again Gordon. This is complex!

GordonBGood said:

Was this done using the monitor menu controls or the Display
Properties? If done using the monitor menu, than you shouldn't
have to use method 2 at the bottom; if done using Display
Properties, you should use method 2 in order to properly view true
sRGB images without colour management such an in Internet Explorer
so that shadow details are as bright as intended.

Click to expand...

Done via Display Props. Not sure where monitor menu controls are?

GordonBGood said:

No, this is the relative gamma to which I referred. Since I
recommend a final monitor gamma of 2.5 and your current monitor
gamma appears to be 1.96, you need to apply a relative gamma
correction of 1.96/2.5 = 0.784 or about 0.78 for viewing in fairly
dim environments (recommended), or 1.96/2.2 = 0.89 for viewing in
bright conditions. If your monitor has a monitor menu setting to
sRGB, this should be all you need to do. If it does not, than you
should perform method two at the bottom of this post.

Click to expand...

Done. Set to 0.78 under Display Props/NVIDIA/Additional Properties/TwinView/Device Settings/Colour Correction/Gamma. But does my "monitor have a monitor menu setting to sRGB" as you have stated above? or should I proceed to method 2 which you recommend. In method 2 you suggested letting windows use the default sRGB profile when none is specified, but I have already specified sRGB, as above. (Sorry to be so dim in interpretting you directions!)
Cheers
David

dchass said:

dchass said:

Was this done using the monitor menu controls or the Display
Properties?

Click to expand...

Click to expand...

dchass said:

Done via Display Props. Not sure where monitor menu controls are?

Click to expand...

A read of the monitor manual might be helpful at this point (or maybe a little before?) ;-/

Most monitors have at least four buttons on their front or side (other than the power button) that are labeled "Menu", "up arrow", "down arrow, "select", and maybe an additional "left arrow" and "right arrow" buttons. Usually pressing the "Menu" button opens up an on screen display (OSD) where you can set such things as various image parameters, although LCD monitors have less parameters that can be set than CRT monitors. Usually two of these buttons are shortcuts to adjust monitor contrast and brightness.

On the Dell website on the page for the Dell UltraSharp 2001FP 20.1" LCD monitor, which I assume is your monitor, I see four smaller bottons and a large button (which I assume to be power) on the lower right corner. These buttons are described as "Input Select, OSD Menu and Select, Minus (-) and Plus (+), Brightness / Contrast, Auto Adjust, Power Button and Indicator". This seems to be seven buttons. Anyway, when you press the OSD Menu one you should see a menu. One of the things you can do with this menu should be reset your monitor to default settings under one of the sub menus.

Also, one of the items you should be able to select using the + - buttons should be Color. Under Color, some monitors have a sRGB setting, which usually locks the contrast and brightness controls to their "best" positions, sets the monitor's white point to D65, and sets the tone curve to the ideal sRGB curve that I simulate using method 2 as described, but with an average value of gamma 2.2 instead of the gamma 2.5 I recommend for viewing in dim environments. If your monitor has this and implements it correctly, you don't need to use method 1 or method 2, and only need to apply a correction of 2.2/2.5 = relative gamma 0.88 inside Display Properties for viewing in dim conditions.

If your monitor doesn't have this setting, also under the Color submenu, there may be controls to set your white balance to a particular white balance colour temperature such as D65 or 6500K (preferred). Alternatively, there may be controls to set colour balance to "Cooler", "Normal", or "Warmer", in which case usually the "Cooler" setting is the closest to D65 for LCD monitors. There will also be a provision to mess with the individual RGB channel gains to get any white balance you want, but this is tricky and best done setting a white on your monitor to a the white on another monitor with a known good exact setting.

Some LCD monitors have another adjustment somewhere in this OSD menu where you can adjust gamma to "Lower", "Normal", or "Higher", and if this monitor has this, you should adjust to the setting that gives you the darkest display (since your monitor has a native 1.96 gamma, which is too bright). You will then have to measure what this gamma is (using Brettel) and adjust accordingly.

dchass said:

dchass said:

No, this is the relative gamma to which I referred. Since I
recommend a final monitor gamma of 2.5 and your current monitor
gamma appears to be 1.96, you need to apply a relative gamma
correction of 1.96/2.5 = 0.784 or about 0.78 for viewing in fairly
dim environments (recommended), or 1.96/2.2 = 0.89 for viewing in
bright conditions. If your monitor has a monitor menu setting to
sRGB, this should be all you need to do. If it does not, than you
should perform method two at the bottom of this post.

Click to expand...

Click to expand...

dchass said:

Done. Set to 0.78 under Display Props/NVIDIA/Additional
Properties/TwinView/Device Settings/Colour Correction/Gamma. But
does my "monitor have a monitor menu setting to sRGB" as you have
stated above? or should I proceed to method 2 which you recommend.
In method 2 you suggested letting windows use the default sRGB
profile when none is specified, but I have already specified sRGB,
as above. (Sorry to be so dim in interpretting you directions!)

Click to expand...

I can't tell if your monitor has a sRGB mode in the OSD menu, but you should know shortly. As for the sRGB setting you have applied under Display Properties/Color Management, there is nothing wrong with using that profile, but Windows will automatically apply that profile if no other is specified. You can remove it if you wish (or not). If you can set your monitor to sRGB in the OSD menu, do so and check the gamma again using Brettel. Use that to apply the relative gamma as 2.5 = relative gamma correction to apply. That would be it.

If there is no OSD menu sRGB mode, but if there is a OSD menu gamma adjustment that darkens the image, you need to measure the new gamma value and let me know so I can calculate a new relative gamma correction curve for that condition using method 2.

If there is no gamma correction in the OSD menu, proceed as described previously with method 2, as the gamma will be as you previously determined.

Note that you have seemingly not yet done a monitor white point colour temperature setting if you have not yet discovered the OSD menu. This is one of the things that make up a proper monitor set up, as often LCD monitors native white point that is too "warm" meaning reddish, where the "native" white point of CRT monitors is too "cool" or bluish. It can be difficult to determine the correct setting if the OSD setting does not provide calibrated options, but take comfort in this: if you are anywhere close, the human visual system adapts for a fairly wide range of errors from about 5000 to over 6500 degrees Kelvin over a few minutes. The main problem would be if you are trying to adjust images to match prints at some exact assumed colour temperature when you have a light source of that exact specification to iluminate the prints.

Regards, GordonBGood

GordonBGood said:

A read of the monitor manual might be helpful at this point (or
maybe a little before?) ;-/

Click to expand...

Sorry Gordon, no manual with my monitor, and unlike you, I have not had the presence of mind to look up the Dell website. I am amazed at your generosity in agreeing to spend so much ime with me. With work pressures, I am v late home tonight and may be so for the next few nights.

GordonBGood said:

Most monitors have at least four buttons on their front or side
(other than the power button) that are labeled "Menu", "up arrow",
"down arrow, "select", and maybe an additional "left arrow" and
"right arrow" buttons. Usually pressing the "Menu" button opens up
an on screen display (OSD) where you can set such things as various
image parameters, although LCD monitors have less parameters that
can be set than CRT monitors. Usually two of these buttons are
shortcuts to adjust monitor contrast and brightness.

On the Dell website on the page for the Dell UltraSharp 2001FP
20.1" LCD monitor, which I assume is your monitor, I see four
smaller bottons and a large button (which I assume to be power) on
the lower right corner. These buttons are described as "Input
Select, OSD Menu and Select, Minus (-) and Plus (+), Brightness /
Contrast, Auto Adjust, Power Button and Indicator". This seems to
be seven buttons. Anyway, when you press the OSD Menu one you
should see a menu. One of the things you can do with this menu
should be reset your monitor to default settings under one of the
sub menus.

Click to expand...

I am v keen to follow this thru and will be back in touch in the next few days.
Regards
David

dchass said:

GordonBGood said:

A read of the monitor manual might be helpful at this point (or
maybe a little before?) ;-/

Click to expand...

Click to expand...

dchass said:

Sorry Gordon, no manual with my monitor, and unlike you, I have not
had the presence of mind to look up the Dell website. I am amazed
at your generosity in agreeing to spend so much time with me. With
work pressures, I am v late home tonight and may be so for the next
few nights.

Click to expand...

dchass said:

I am v keen to follow this thru and will be back in touch in the
next few days.

Click to expand...

David, I'd like to see this through with you. I have been thinking of resurrecting my web site and putting this information in it so that anyone could use it, as it's a problem that often comes up, and many don't understand all of the intricacies. So the time spent isn't wasted, as I may be able to help many with this effort.

I poked around a little further on the Dell website, and found documentation for three monitors of this size, the 2000FP, the 2001FP, and the 2005FPW, which also has sound and is wide screen so isn't your monitor. For the 2001FP, which is likely your monitor, there is a downloadable PDF manual at: http://support.dell.com/support/edocs/monitors/2001fp/EN/DELL-QSG-EU.PDF . Also PDF's for the others. None of them appear to have a true sRGB setting, nor do they have a gamma adjustment. The 2000FP does have a calibrated setting to 6500K, which is good. The other two just have normal, red, and blue presets. In the case of the 2001FP, from what I read, I suspect that the red preset may be the one closest to 6500K, but it may be the normal setting which is closer. With the 2005FP monitor, they have renamed the normal preset with an added (sRGB), so one would think that it might be D65/6500K. I suppose that I would leave these settings to the normal setting unless you find that the whites are quite blue as compared side-by-side with another monitor with a 6500K setting, in which case you would switch to the Red preset, or use the User presets to tweak the individual RGB gains, which is quite tricky.

So it looks like you do need method 2) as I calculated for you. A further thought is that this method (2) maps the full sRGB tonal range onto the limited 400:1 contrast range of your monitor, as the full range of your digital images is normally mapped onto the limited range of prints, whose dynamic range is limited by how reflective the blacks is and how white the paper is. There is another way of mapping to show true luminances, which I will now call method 3).

Method 3) recalculates the curves based on the information you have given me so that any luminance that can be shown on your monitor will be shown, but dark shadows that are beyond the dynamic range of your monitor will be black. In this way, those tones that are shown will be at their correct luminances, but you will have some of the shadow details "blocked out". For instance, the last two 'Y' and 'Z' blocks on the tone bar at the bottom of the reviews on this site will both appear to be as black as it gets. Because we don't use much of the shadow detail area that needs a boost, we can approximate this curve much more easily. We just change the position of the square box point that usually marks the (0, 0) co-ordinate on the gamma chart in Advanced Color Profile mode to the (in, out) co-ordinates of (0.06, 0.00) and use only one point at the co-ordinates (0.45, 0.36) to define the curve, leaving the top square box point at (1.00, 1.00). This is for your measured native montor gamma of 1.96 in order to convert it to a gamma 2.5 for viewing in dim environments but with the black point compensation applied so that the blacks that are out of the contrast range of your monitor will be black.

Let us know how it goes!

Regards, GordonBGood