RAW vs JPG test -- huge difference?

I took some test shots (RAW+JPG) with the XT, and then compared the pics using Picasa's viewer which now supports CR2 files.

There were big, unexplainable differences. Parameters on camera were set at 0 (not -2), but exposure difference was huge. Can anyone explain these? I converted RAW to JPG to view here, and they look identical to original RAW.

The first is RAW (originally), the second, JPG:





--
Sam Kanter, NYC

Exposure is the same, but Picasa is apparently using a different (gamma) curve during conversion of the linear data to sRGB space.

--
Geir

Ladehaug said:

Exposure is the same, but Picasa is apparently using a different
(gamma) curve during conversion of the linear data to sRGB space.

Click to expand...

Well, not that I know exactly what that means, but I took about ten RAW+JPG test shots. Some looked identical, some the RAW were much brighter, on some the JPG was brighter.

Would different gamma curve explain those seemingly arbitrary differences?

--
Sam Kanter, NYC

skanter said:

Well, not that I know exactly what that means,

Click to expand...

Initially the sensor is capturing light linearly. In order to view this 'the right way' on a monitor screen it is necessary to apply a gamma curve. You can further adjust the gamma curve by using levels or curves in Photoshop.

You can read more about this here:
http://www.normankoren.com/digital_tonality.html

skanter said:

but I took about ten
RAW+JPG test shots. Some looked identical, some the RAW were much
brighter, on some the JPG was brighter.
Would different gamma curve explain those seemingly arbitrary
differences?

Click to expand...

Well, that is a bit strange. I've never used Picasa, so I have no idea what is going on with that program. I'm using DPP (Canon Digital Photo Professional) to convert RAW. It's in my opinion the best RAW converter and it's giving the most accurate colors.

--
Geir

Ladehaug said:

Ladehaug said:

Well, not that I know exactly what that means,

Click to expand...

Initially the sensor is capturing light linearly. In order to view
this 'the right way' on a monitor screen it is necessary to apply a
gamma curve. You can further adjust the gamma curve by using levels
or curves in Photoshop.

You can read more about this here:
http://www.normankoren.com/digital_tonality.html

Ladehaug said:

but I took about ten
RAW+JPG test shots. Some looked identical, some the RAW were much
brighter, on some the JPG was brighter.
Would different gamma curve explain those seemingly arbitrary
differences?

Click to expand...

Well, that is a bit strange. I've never used Picasa, so I have no
idea what is going on with that program. I'm using DPP (Canon
Digital Photo Professional) to convert RAW. It's in my opinion the
best RAW converter and it's giving the most accurate colors.

Click to expand...

Have you ever done a RAW+JPG test to see the differences between
the two? I'd be curious of the results using DPP instead of Picasa...

--
Sam Kanter, NYC

brand new 350d user here and 1st time using RAW... I shot a bunch of photos yesterday in RAW + JPG and viewed them using Photoshop CS2. The RAW versions were sometimes a bit brighter. But, most of the time, they were pretty much the same - certainly nowhere near the difference that yours show.

in that case I prefer the .jpg version. I think you pushed the contrast a bit too much in the RAW conversion.

skanter said:

I took some test shots (RAW+JPG) with the XT, and then compared the
pics using Picasa's viewer which now supports CR2 files.

There were big, unexplainable differences. Parameters on camera
were set at 0 (not -2), but exposure difference was huge. Can
anyone explain these? I converted RAW to JPG to view here, and they
look identical to original RAW.

The first is RAW (originally), the second, JPG:





--
Sam Kanter, NYC

Click to expand...

--



Please do not start new thread for private message to me but send them to me via email instead! thanks.

Daniella said:

in that case I prefer the .jpg version. I think you pushed the
contrast a bit too much in the RAW conversion.

Click to expand...

As a finished product, perhaps, but it seems like the jpg version has lost a lot of detail in the clouds.

While Picasa is a great tool, it doesn't do a very good job displaying RAW images. A better comparison would be to take the .jpg file and compare it to the corresponding raw file that you run through a raw converter like C1 or RSE, without making any adjustments. My experience is that Picasa renders the raw files differently from every other raw processor I have used. I don't depend on Picasa to handle any processing on my raw files, while I can do about 80% of my .jpg pp in Picasa.

Cheers,

Jim
--
Gallery at:
http://www.pbase.com/borderrose/viewgallery

Daniella said:

in that case I prefer the .jpg version. I think you pushed the
contrast a bit too much in the RAW conversion.

Click to expand...

I didn't push -anything-. Picasa did the conversion all by itself, there were no choices to be made. Seems to me that the sky was washed out in the jpg version, and I would certainly prefer the RAW in this case.

Daniella68313 said:

skanter said:

I took some test shots (RAW+JPG) with the XT, and then compared the
pics using Picasa's viewer which now supports CR2 files.

There were big, unexplainable differences. Parameters on camera
were set at 0 (not -2), but exposure difference was huge. Can
anyone explain these? I converted RAW to JPG to view here, and they
look identical to original RAW.

The first is RAW (originally), the second, JPG:





--
Sam Kanter, NYC

Click to expand...

--



Please do not start new thread for private message to me but send
them to me via email instead! thanks.

Click to expand...

--
Sam Kanter, NYC

You might try Picasa again with v2.1. We've improved color balance considerably, and our results should be reasonably good compared to other programs.

And our speed is really fast. We don't use embedded JPEGs even for previews -- we always work from the raw data.

mherf said:

You might try Picasa again with v2.1. We've improved color balance
considerably, and our results should be reasonably good compared to
other programs.

And our speed is really fast. We don't use embedded JPEGs even
for previews -- we always work from the raw data.

Click to expand...

I DID use Picasa v2.1.

--
Sam Kanter, NYC

There is always http://www.normankoren.com/digital_tonality.html but there are lighter reads as well if you Goog..um msn search for them.

You are comparing two images with different tonality curves/RAW conversions applied to them. One was applied in-camera, one was applied in Picasa. Do you know what the camera's conversion yields on its default settings? Do you know what Picasa's default ocnversion yields?

It's not surprising to get different results from different software, it's part of the benefit of having the RAW images so tweakable.

I agree, I just installed 2.1 Good job on improving the RAW handling!!!

If you can pass along user desires for 3.0 please add:

1. a slider for the sharpen function. You current sharpening effect is too strong.

2. the ability to lighten shadows in addition to the current capability to darken them. All you would need to do is set the current slider's default position in the middle of the slider range and let movement to the left lighten shadow detail in the displayed image

3. the ability to darken highlights in addition to the current ability to lighten them. Use the same "slider in the middle" as described above.

4. ability to have fill light uniformly darken an image in addition to it's current capability to lighten the image. Same slider use as above.

You have the absolute best human engineered application ever written, bar none. These additional capabilities can be added without compromising the applications simplicity or user interface.

Cheers,

Jim
--
Gallery at:
http://www.pbase.com/borderrose/viewgallery

Oooh, is this a live Picasa developer? Where can I send rants about nasty UI behaviors with files, folders, and the like?

BTW, I love the software, but some things are maddening -- and all the more so because they're so simple to fix.

borderrose said:

I agree, I just installed 2.1 Good job on improving the RAW
handling!!!

If you can pass along user desires for 3.0 please add:

1. a slider for the sharpen function. You current sharpening
effect is too strong.

2. the ability to lighten shadows in addition to the current
capability to darken them. All you would need to do is set the
current slider's default position in the middle of the slider range
and let movement to the left lighten shadow detail in the displayed
image

3. the ability to darken highlights in addition to the current
ability to lighten them. Use the same "slider in the middle" as
described above.

4. ability to have fill light uniformly darken an image in
addition to it's current capability to lighten the image. Same
slider use as above.

You have the absolute best human engineered application ever
written, bar none. These additional capabilities can be added
without compromising the applications simplicity or user interface.

Click to expand...

I'll second the sharpening problem. Just ONE option, on or off, and it's much too strong? At least make it a very subtle sharpening, as one can keep repeating it anyway!

How about clone tool? Nothing fancy, but this is needed quite often.

Thanks...

--
Sam Kanter, NYC

Sam, from my limited use of RAW it seems to be that Canon's Raw Image Task (part of zoombrowser) processes its RAW files to jpg the same way the camera processes its image to jpg. (as long as you keep all of the in camera settings and make no adjustments).

To me, the other two programs I have looked at, Canon DPP and Raw Shooters Essential do limited processing to the viewed photo, they do not seem to keep in camera settings as the starting point.

So, to look like in camera processing use RIT, the other programs allow more adjustments.

To save memory, I shoot RAW, convert to jpg using RIT, then once I start understanding RAW conversion a little more I will use RSE or DPP (have not tried version 2.0 yet) to adjust the RAW file on the images I think need more adjustment to my liking.

Tony

300D, kit lens, ISO100, F8, 1/640, daylight wb, contrast/saturation/sharpening set to 0 (= parameter 1). It is underexposed in the first place, so equal amounts of levels (0 - 1.0 - 230) in PS was added to the outputs. The images are almost identical but the color balance is slightly different. It's hard to see here, but DPP is slightly more aggressive to the highlights (a more pronounced shoulder in the gamma curve).

Now, doing some 'heavy' PP to bring out the shadows leads to this result:



Notice the greenish cast in the JPG version. The DPP version is more color accurate. Here's a closer look:



The DPP conversion was output to a 8 bits TIF only, and then post processed exactly the same way as the JPG, but even at this stage the DPP result is clearly superiour to the JPG version. Even better results can be achieved by using 16 bits.

The newest version of DPP added some 'picture styles' that can be used to add different color balances to pictures. Two examples:



Other picture styles included: standard (as shown in the comparison), portrait, faithful and monochrome. The newest version of DPP is an improvement, but I still miss more specialized tools for adjusting highlights and shadows. I can do those adjustments in PS, but it'd be great to do everything in one program.



Final post processed image.

Another comparison example showing differences in skin tones from standard JPG versus DPP:



F8, 1/400, daylight wb, parameter 1. Straight outputs with no other PP than resizing / cropping. The JPG version has, what I call it, the typical greenish cast in the shadows. It's really hard to notice it without having something to compare it to. When comparing it to the DPP output, one can surely see the difference - the DPP output is more color accurate.

--
Geir