colour management in photoshop

[freelancer]

Open up the original file. See the color picker values for say #1 (RGB : 70,85,183). The color picker pop up will have 'Warning : out of gamut for printing" and "Warning : not a safe web color". If you click on these warning icons the RGB values will change.

 

[jopel]

In photoshop,

1. View --> Proof Setup --> Monitor RGB
2. CTRY-Y (or View --> Proof Colors)

Each time you hit CTRL-Y you are turing the image soft proof 'on' and 'off'. Pay attention to the area where the white stripes are and you should see a slight shift from pale purple to deep blue. Certainly its not the bright purple as above which is from an edited image where I believe during the editing workflow, the Green and Blue channel were clipped and not the Red channel. The histogram shows that the Green and Red channels were much closer to the right hand side than the Red channel.

If you use Image -- > Adjustment --> Color Balance in photoshop and move the Red slider to say -30, the 'pruple' will turn 'blue' as shown in the original post (right hand image).

It is quite interesting that the original poster raised this discussion because unless you get hit onto it, it is easily missed. My opinion are that even if you shoot in sRGB, its always best to convert to Adobe RGB and 16 bits when you do color editing work where good color reproduction is important. Once editing is done, its alright to convert back to sRGB and 8 bits to save. Nothing to loose but avoids potential issues like this one.

I actually found out about this Adobe RGB/16 bits the long way. Did a lot of prints with various combinations and color patches and its quite evident that converting to sRGB will shift colors particularly reds. Nowadays even when I send my images for outside printing its always on Adobe RGB color space. Most digital printers (Kodak Noritsu, Fuji Frontier) can print much bigger than the sRGB color space.

yes there will be colour shift when we convert or assign a different profile but not so drastic as what +evenstar having.

i don't think his is a colour shift problem. it could be some setiings that are wrong or the colour profiles are corrupted.

 

[theRBK]

It is quite interesting that the original poster raised this discussion because unless you get hit onto it, it is easily missed. My opinion are that even if you shoot in sRGB, its always best to convert to Adobe RGB and 16 bits when you do color editing work where good color reproduction is important. Once editing is done, its alright to convert back to sRGB and 8 bits to save. Nothing to loose but avoids potential issues like this one.

I actually found out about this Adobe RGB/16 bits the long way. Did a lot of prints with various combinations and color patches and its quite evident that converting to sRGB will shift colors particularly reds. Nowadays even when I send my images for outside printing its always on Adobe RGB color space. Most digital printers (Kodak Noritsu, Fuji Frontier) can print much bigger than the sRGB color space.

Actually, if you convert to Adobe RGB 16 bit, do your colour adjustment, then save to sRGB 8bit, you are gonna create the situation where you might lose colour that can be represented in Adobe RGB 16bit but that is out of sRGB 8bit gamut...what is the gain in the converting to Adobe RGB then?

And from what I have read on the web (can't find the sites but here is one that is useful as well http://www.drycreekphoto.com/Learn/additional_profile_questions.htm) printers today can cover most of sRGB but not of Adobe RGB...so applying Adobe RGB is gonna leave room for colour misrepresentation when the machines try to compensate...so its still safer to give sRGB if you want to maximise the possibility of having WYSIWYG print of your images. The colours might not be as vibrant but you run less risk of shifts.

 

[freelancer]

theRBK, it depends on what you do during post processing and color accuracy. In this example, the original colors were (I suspect) at the edge of the sRGB color space. Editing in a bigger color space like Adobe RGB and then converting back to sRGB gives you more headroom to play around with color numbers. If you are not too concerned with accurate color reproduction, I would agree that sRGB is the best place to edit.

It also depends on the medium where you are going to use the image, if its printers then I would use a color space bigger than sRGB. Even Canon printers use the EXIF information to determine color values outside of sRGB. The DryCreekPhoto site has some good color space charts for various printers and all of them if I recall correctly have a color space larger than sRGB.

When converting from a bigger color space like ProPhoto or Adobe RGB to sRGB, you can have control how the color numbers are translated and into the final WYSIWYG,
- Perceptual
- Saturation
- Relative Colorimetric
- Absolute Colorimteric

Normally I use Perceptual or Relative Colorimetric.

Editing is always a 'destructive' process and when converted to 16 bit and then back to 8 bits, you actually benefit from the 16 bit space in terms of lesser information lost in the process. A simple test is to do levels using at 8 bit and 16 bit. The 16 bit histogram looks smoother.

jopel, you are right in that the color shift should not be this much. I found out from the original poster that he did a quick edit in a non-color aware application. Because the 'purple' was at the edge of the color space it just made the difference this much apparent.

 

[+evenstar]

thanks guys for the feedback..i'll send one of my prints one of these days to the lab for printing and see what i get with different settings...

freelancer: somehow i prefer the colours with proofing for Monitor RGB...looks more natural...

 

[theRBK]

Sorry to the TS for the OT

theRBK, it depends on what you do during post processing and color accuracy. In this example, the original colors were (I suspect) at the edge of the sRGB color space. Editing in a bigger color space like Adobe RGB and then converting back to sRGB gives you more headroom to play around with color numbers. If you are not too concerned with accurate color reproduction, I would agree that sRGB is the best place to edit.

Accuracy is one thing, reproduceability on the final medium is another. Editing in a bigger colour space might give more headroom, but if the final image has colours that cannot be reproduced in sRGb, then it is quite pointless...

It also depends on the medium where you are going to use the image, if its printers then I would use a color space bigger than sRGB. Even Canon printers use the EXIF information to determine color values outside of sRGB. The DryCreekPhoto site has some good color space charts for various printers and all of them if I recall correctly have a color space larger than sRGB.

The printer gamuts may be larger (in certain areas)than sRGB, but they are significantly smaller than Adobe RGB, which again brings us to the problem of reproduceability...having experienced the frustration of converting RGB to CMYK for process prints, when the colour is out, no amount of conversion with whatever engine is gonna help...if the colours are not reproduceable in the printers gamut there is little anyone can do...it helps if you have a lab or printer you trust and who can help do the final conversion to the printer's profile, and but even they would only be able to reduce the damage... and there goes a bit of colour accuracy...

 

[freelancer]

freelancer: somehow i prefer the colours with proofing for Monitor RGB...looks more natural...

I know what you mean. I did play around the color balance particularly the Red channel by dialing in a negative value. The shirt color looked much better and did not see much change in the other colors too. Thought that the skin tone looked pretty natural also

 

[freelancer]

theRBK, I am not disagreeing with you. I would if I do not share your point of view

CYMK is a different animal entirely since the color gamut is small. Perhaps I should just mention where I am coming from. I print mainly on a Kodak Noritsu machine or a good quality photo printer and its mainly 8 x 10.

In case you are wondering, as an experiment, together with the manager of the store with the Kodak machine, did ran a sample of color checker file using Adobe RGB and sRGB profiles. There are some visible differences in the way some colors came out. In case anyone is wondering, the DryCreek site has a copy for download or you can go to Tim Grey's site and download his PhotoDisc test chart.

I know this may be a little off topic but reckon a different point of view perhaps is appreciated for the discussion. Always learning new things. Some useful references that guided my understanding (and the RBK, please accept that I am posting the links because it had helped me and not to disagree or agree on the points you raised - in the spirit of sharing and learning)

Norman Koren
http://www.normankoren.com/color_management.html
http://www.normankoren.com/color_management_4.html

Andrew Rodney
http://www.digitaldog.net/

Bruce Fraser
http://www.creativepro.com/author/home/40.html
the article Out of Gamut: The High-Bit Advantage is quite interesting

EXIF Print (sRGB and sYCC)
http://www.cipa.jp/exifprint/contents_e/01exif4_e.html

 

[theRBK]

I understand what ya say, just that for those who aren't aware of the implications, they may wonder about the possible shifts...

positive discussion is always :thumbsup: unlike all those ranting and personal attacks and insulting each other threads

Again sorry to TS for OT :embrass:

 

[+evenstar]

theRBK: no worries...the more we share, the more we learn from one another...

freelancer: can you resend your edited image to me?

 

[freelancer]

freelancer: can you resend your edited image to me?

You got mail

 

[+evenstar]

did some recalibration, colour is slightly better, but still purplish ...will be going down to print some test samples soon..

guess i've gotta live with it for the time being