Color management

SteveS · Posted: Sat Apr 30, 2005 3:41 pm Post subject: Color management

For the first time, I am having large Lightjet prints made, which require using the Lightjet color space. My first attempt, the test prints were way off. My monitor is calibrated using Adobe gamma, but I believe it is quite accurate.

I had some Lambda prints done a few months ago, which did not require a color space, just adobes native space, and they came out a perfect match to what I expected.

Any advice on working with color management in Photoshop (6)?

SteveS · Posted: Mon May 02, 2005 7:59 pm Post subject:

Okay then - how bout this one.

I have been using the default Photoshop 6 color space of sRGB 1EC61966-2.1.

I have not messed with the color settings.

I typically scan in slides (Minolta Dimage Scan Elite) to prepare for inkjet printing, and then to downsize, and prepare for the web. Up to now, everything seems to be fine. If anybody has a moment, please take a look at some of the pictures on my website http://www.steveshamesphotos.com and see if you think there is potential for the colors to be better.

My question is, should I change the color space to Adobe RGB (1998)?

I noticed it does present more saturated colors, but what ramifications would this have for the inkjet printer, or for preparing JPEG's for the web?

In other words, what advantages outside of Photoshop, does using Adobe RGB (1998) provide?

cbadland · Posted: Mon May 02, 2005 8:12 pm Post subject:

AdobeRGB offers a larger color range (gamut) than sRGB. A straight sRGB>ARGB conversion won’t help too much just to go to inkjet print (it won't hurt). But converting sRGB>ARGB is a bad idea for web bound pics. A good rule of thumb is to do the opposite: capture and edit in a wide space (like ARGB), convert to sRGB for web use only. Certainly keep the original ARGB file for inkjet bound images.

A must-have book to help you with this (hard to grasp) subject is Real World Color Management by Bruce Fraser et al.

gbf1lm · Posted: Mon May 02, 2005 9:04 pm Post subject:

imho adobe gamma is crap. if your serious, spend some money on a hardware calibration unit. use a calibrated printer, with its specified paper.

SteveS · Posted: Tue May 03, 2005 12:12 am Post subject:

cbadland - Yes, I follow what you are saying, but I guess my main point is - what’s the point?

When I set my color space to Adobe RGB, and opened several images I had previously edited in sRGB, they looked like 10 - 20 points of saturation had been added. If I had to send any to the printer, or prepare for the web in that space, I would certainly have to subtract 10 - 20 points of saturation so that they would look realistic. I sometimes add saturation to an image since a scan seems to "dull" out an image frequently. I guess in Adobe RGB that would not be as necessary, would you agree with that?

Whatever color space I use, I would probably achieve the same results, whether I add saturation in sRGB, or not in Adobe RGB.

I will set my scanner to Adobe RGB and give it a try. What about Joe Holmes Ektaspace? Now THAT is some heavy-duty saturation.

So after printing, you recommend converting to sRGB for the web, would that be in the image > mode > convert to profile? Or just reset the color setting to sRGB? If I reset to sRGB, then I would probably have to subtract saturation, as a step in preparing the larger print file, to the smaller web file.

Am I making sense here? Or am I way off?

cbadland · Posted: Tue May 03, 2005 6:47 am Post subject:

“they looked like 10 - 20 points of saturation had been added.”

You are doing it wrong. You shouldn’t see any difference. It sounds like you are Assigning ARGB instead of Converting. Never Assign a color-space profile to a file you know is a different color-space.
The advantage in using ARGB is the wider gamut available in capture and editing of the image. It is not something you tag on at the end to get a better print.
(Peruse this for advice from someone who knows a lot more than I: http://www.gballard.net/psd/assignconvert.html)

For web images, convert ARGB to sRGB and use Save for Web. If you don’t do that your images may look under-saturated and washed-out when displayed in a browser. (or just use sRGB)

cbadland · Posted: Tue May 03, 2005 7:05 am Post subject:

Language translation is a good way to exemplify this:
Take the word “once”. If it is tagged English, we know it means “one-time.” If it is tagged Spanish, we know it means “eleven.”

If we take the Spanish “once” and CONVERT it to English, it will become “eleven”. It this case the INTENT and MEANING are preserved.

If we take the Spanish “once” and ASSIGN English to it, the word stays the same, but its original INTENT and MEANING are lost.

When you ASSIGN AdobeRGB to a sRGB file, the RGB numbers stay the same (even though it looks different on your monitor) But the INTENT is lost (so normal skin color turns orange.)

SteveS · Posted: Tue May 03, 2005 12:41 pm Post subject:

Yes, I did make the mistake on my first attempt of "assigning" a colorspace, from Joe Holmes Ektaspace to the Lightjet space, and then I did the editing. Those test prints came back awful.

I started over on the drum scans, and this time did all the editing in Joe Holmes Ektaspace and then "converted" at the very end to the Lightjet space. I still await those test prints.

That is an interesting analogy about the word "once"

cbadland · Posted: Tue May 03, 2005 1:19 pm Post subject:

For that particular analogy, I have to credit Ramón over in the Adobe forums.
Good luck.
Nice images on your site; make me miss CA even more.

SteveS · Posted: Wed May 04, 2005 9:37 pm Post subject:

Okay, so the proper workflow should be - scan into Adobe RGB color-space, edit and print in Adobe RGB, and then when downsizing those large edited TIFF print files into JPEG's for the web, “convert” (not “assign”) to sRGB.

Now wouldn’t that embed a color space (sRGB) to the file? What would be the ramifications of that for web intended JPEG's?

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