New article on color management

Started Apr 26, 2013 | Discussions thread
gollywop
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Re: Since I have you here...
In reply to Great Bustard, Apr 27, 2013

Great Bustard wrote:

gollywop wrote:

Great Bustard wrote:

gollywop wrote:

Great Bustard wrote:

gollywop wrote:

Great Bustard wrote:

gollywop wrote:

For better or for worse, I have just published a new article: Color Management - a Walkthrough. It can be found at

http://www.dpreview.com/articles/7270088913/color-management-a-walkthrough

This is a subject I need a great deal of education in -- I'm glad to see such a comprehensive article on the subject!

Turnabout's fair play.

many thanks, GB

...let me ask you a question.  If someone worked entirely in sRGB to produce a print, under what circumstances might working in a different color space result in a "significantly better" print?

Am I to assume here that the shot was taken as a jpeg in sRGB, or are we shooting raw?

RAW, of course.  What's jpg, by the way? 

If it starts out life as an 8-bit sRGB jpeg, there isn't much sense in going anywhere else.

If you've shot raw and your printer has a gamut larger than sRGB, then you'll do better, when processing images that have saturated red, oranges, and/or blues, using a wider space, at least Adobe RGB.  This would often be the case for your red roses or dayglo orange graffiti or cobalt blue underwear.

If you've got a wide-gamut monitor that is capable of a broader gamut than sRGB (otherwise forget it), you can see just what is likely to happen by opening your Adobe RGB-processed file in PS, duplicating it and soft proofing the duplicate using the sRGB profile.

So, unless your monitor can work in a colorspace other than sRGB, you're better off just staying in sRGB?  That is, can't the RAW converter and/or editor work in aRGB and approximate the results on an sRGB monitor, yet still retain the advantages of working in a larger color space?  Or are you saying that unless your monitor can display the larger color space, any conversion or editing you do in sRGB will be counterproductive?

No, not really - at least if you're processing for print and your printer can outstrip sRGB to some degree.  But then your limited monitor will have you flying somewhat blind in the processing and will only be able to see the effects after the fact in the print.

Toggling between the two will give you an idea of what is possible. Or, even more simply, use the Convert (to sRGB) dialog and toggle the Preview checkbox.  If you see no important changes, then using the wider gamut hasn't bought you much, if anything.

I'm not sure what you're saying here.  How do you toggle between colorspaces if your monitor can only handle sRGB?  Or are you saying toggle between color spaces on a monitor that can display both color spaces?

Yes, the latter.

Clearly, if your monitor's gamut is roughly sRGB, you'll not be able to see any effect even if it exists.  This is even more true for a gamut like ProPhoto RGB. No monitor is going to let you see a lot of what might be happening by using this space.  Similarly, if your printer's gamut is close to sRGB, there is not likely to be any advantage in using a wider working space.  The conversion will be done by the printer's profile and you'd be better off controlling it yourself prior to printing.

Sounds to me like what you're saying is you should only work in the colorspaces that are common to all the devices in the imaging chain.  Is this correct?

As I indicted above, if the printer has a gamut larger than the monitor, you might try, somewhat blindly, to take advantage of it.  Some computer monitors have a really poor gamut, much less than a good inkjet printer. That combination would clearly put you at a real disadvantage, and I suspect it's not all that uncommon.

I've got a number of sunset shots with saturated oranges that I've processed with both sRGB and Adobe RGB, and the differences are quite noticeable from my Canon PixmaPro 9000 II (particularly when using Red River papers).  The sRGB results are dull and disappointing.

So, I take it that both your monitor and printer can work in aRGB?

Yes.

OK -- good stuff!  I have two followup questions:

  1. Are there monitors and printers that do PPRGB?  If so, what do they cost? 
  2. What role does the paper the photo is printed on play in all this?

I think (but am not 100% positive) the most ambitious gamut for monitors is NTSC, which is a bit wider than Adobe RGB. That gamut is, I think, supposed to be the best that a CRT can produce.  I know there are supposed to be monitors that are NTSC, but they are in the thousands.  I've never really looked that direction.

And, if you're going to go in that direction, you want more than just the monitor.  You've got to control the room ambient lighting to a fare-the-well and do the monitor calibration taking it into account.

sRGB is about 72% of NTSC and the decent wide-gamut LCDs available today get upwards of 95-98%, and pretty well encompass Adobe RGB.

NTSC is only about 54% of LAB, whereas ProPhoto RGB is 91%.

As to papers, wow!  They can differ in so many ways that one doesn't know where to start.  Decent glossy papers (I love Red River) have some of the best reflectance and can provide the best reflective DR.  But different glossy papers also differ in how well they take inks, etc.  Many people forgo DR for artistic effect and love to use matte and other textured papers.  And, then, of course, there are major differences in pigment vs. dye inks.

That's why it's so important that, when printing, you use a printer profile that is matched not only for the printer but the paper.

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gollywop

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