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Author Topic: converting to a color space getting a weird change in colors?  (Read 2496 times)
lightstand
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« on: March 15, 2009, 04:01:19 PM »
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First I just upgraded to CS 4 from CS 3 and am thinking I must be overlooking some preference.  Let's say I bring a RAW capture set to sRGB into Photoshop then under the edit menu convert the file to sRGB to me no change should happen however when i do this I am getting a very weird color shift. Even if I was converting an Adobe RGB image to an sRGB space I wouldn't expect nor have I ever seen such a dramatic shift in the colors.

Color Management Policies:   Preserve Embedded Profiles
Coversion Options:               Adobe Ace Engine,
Intent:                                Relative Colorimetric
Checked:               use Black point Compensation
                             Use Dither (8-bit)
                             Compensate for Scene-referred profiles



 Any suggestions or insights what I should look at to see if everything is set up correctly? thanks jeff
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PeterAit
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« Reply #1 on: March 15, 2009, 05:51:44 PM »
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Quote from: lightstand
First I just upgraded to CS 4 from CS 3 and am thinking I must be overlooking some preference.  Let's say I bring a RAW capture set to sRGB into Photoshop then under the edit menu convert the file to sRGB to me no change should happen however when i do this I am getting a very weird color shift. Even if I was converting an Adobe RGB image to an sRGB space I wouldn't expect nor have I ever seen such a dramatic shift in the colors.

Color Management Policies:   Preserve Embedded Profiles
Coversion Options:               Adobe Ace Engine,
Intent:                                Relative Colorimetric
Checked:               use Black point Compensation
                             Use Dither (8-bit)
                             Compensate for Scene-referred profiles



 Any suggestions or insights what I should look at to see if everything is set up correctly? thanks jeff

As I understand it, a RAW capture cannot be "set to sRGB" (or any color space). When you set your camera to sRGB, it means that if you convert the image to JPG in the camera, the resulting JPG will use sRGB. So, a RAW does not have an embedded profile to preserve. When you open a RAW, PS will use the color space you select under Working Spaces:RGB, which should be Adobe RGB or, even better, ProPhoto RGB.

Let's say you have it set for Adobe RGB. When you open a RAW, PS translates the data in the RAW into colors in the Adobe RGB space.  THis space is quite a bit larger (contains more colors) than sRGB, so when you convert to sRGB some of the colors change.

Hope this helps,

Peter

Peter
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Peter
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Mark D Segal
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« Reply #2 on: March 16, 2009, 07:20:32 AM »
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What is your working space set to in Photoshop? Do you have profile mismatch warnings turned on in your Color Settings in PS? Camera Raw shows the image in ProPhoto Understanding ProPhoto-LL. In ACR, the working space selection only affects the rendering of the image, not how it looks in ACR. It will open in PS tagged with the profile you selected in ACR. So if you selected sRGB in ACR, when the file opens in PS it is tagged with an sRGB color space profile. There is no more conversion which needs to be done if you wish to keep it in sRGB provided you have Preserve Embedded Profile selected in your Color Settings. However, if you open an sRGB file into a ProPhoto working space you should get a mismatch warning. if you have chosen to be warned about mismatches. If you want to move a file tagged sRGB into a wider space (e.g. ARGB98 or ProPhoto), having clipped so much colour by selecting sRGB in the first place, converting it to a wider space could produce weird effects. Best practice is to set ProPhoto as your default working space in Photoshop, and in ACR, tag the image with ProPhoto. This is particularly recommended if you are printing images in a current inkjet printer. The most recent Epson professional printers have segments of gamut exceeding even ARGB(98) and approaching ProPhoto. For web and email, you can slim-down the image to sRGB - Photoshop handles this process well if you do it correctly.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
lightstand
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« Reply #3 on: March 16, 2009, 07:50:03 AM »
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Quote from: MarkDS
What is your working space set to in Photoshop? Do you have profile mismatch warnings turned on in your Color Settings in PS? Camera Raw shows the image in ProPhoto Understanding ProPhoto-LL. In ACR, the working space selection only affects the rendering of the image, not how it looks in ACR. It will open in PS tagged with the profile you selected in ACR. So if you selected sRGB in ACR, when the file opens in PS it is tagged with an sRGB color space profile. There is no more conversion which needs to be done if you wish to keep it in sRGB provided you have Preserve Embedded Profile selected in your Color Settings. However, if you open an sRGB file into a ProPhoto working space you should get a mismatch warning. if you have chosen to be warned about mismatches. If you want to move a file tagged sRGB into a wider space (e.g. ARGB98 or ProPhoto), having clipped so much colour by selecting sRGB in the first place, converting it to a wider space could produce weird effects. Best practice is to set ProPhoto as your default working space in Photoshop, and in ACR, tag the image with ProPhoto. This is particularly recommended if you are printing images in a current inkjet printer. The most recent Epson professional printers have segments of gamut exceeding even ARGB(98) and approaching ProPhoto. For web and email, you can slim-down the image to sRGB - Photoshop handles this process well if you do it correctly.

Thanks for the replies. Sorry about being vague. I have my work space set at sRGB. I am tagging my raw file in ACR as an sRGB profile and when I'm in Photoshop and convert the file to sRGB (yes I know I don't need to do this - I'm trying to figure out why I'm getting a shift) the file is sRGB & was sRGB why then am I getting a weird color shift when I perform the convert?  Again I realize I don't technically need to do this redundant convert however I have to figure out why this is happening because it is screwing up my ability to save for web. I truly appreciate any ideas or suggestions. thanks jeff

p.s. i have tried this with psd files and yes I normally work in the ProPhoto or aRGB colorspace
« Last Edit: March 16, 2009, 07:52:37 AM by lightstand » Logged
Mark D Segal
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« Reply #4 on: March 16, 2009, 08:04:23 AM »
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Quote from: lightstand
Thanks for the replies. Sorry about being vague. I have my work space set at sRGB. I am tagging my raw file in ACR as an sRGB profile and when I'm in Photoshop and convert the file to sRGB (yes I know I don't need to do this - I'm trying to figure out why I'm getting a shift) the file is sRGB & was sRGB why then am I getting a weird color shift when I perform the convert?  Again I realize I don't technically need to do this redundant convert however I have to figure out why this is happening because it is screwing up my ability to save for web. I truly appreciate any ideas or suggestions. thanks jeff

p.s. i have tried this with psd files and yes I normally work in the ProPhoto or aRGB colorspace

Jeff, if you don't need to do something because it is redundant, don't do it, create your web images directly from what you've exported to PS and see whether this makes your imaging life easier/more satisfactory.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
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« Reply #5 on: March 16, 2009, 12:49:07 PM »
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Quote from: lightstand
Again I realize I don't technically need to do this redundant convert however I have to figure out why this is happening because it is screwing up my ability to save for web.
p.s. i have tried this with psd files and yes I normally work in the ProPhoto or aRGB colorspace

Have you tried disabling the Convert to sRGB checkbox in the save for web dialog?

I do agree that if your image is already sRGB and you "convert" to sRGB you should see no changes.  I assume when you are selecting convert to profile, both profiles listed at identical?
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lightstand
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« Reply #6 on: March 16, 2009, 01:19:41 PM »
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Quote from: Wayne Fox
Have you tried disabling the Convert to sRGB checkbox in the save for web dialog?

I do agree that if your image is already sRGB and you "convert" to sRGB you should see no changes.  I assume when you are selecting convert to profile, both profiles listed at identical?

 Yes and this isn't just sRGB if I convert a file that is tagged as ProPhoto & convert it redundantly to ProPhoto I get the shift.  I honestly never remember having any image shift this noticeably prior to CS 4 so what preference would be different now that I've upgraded? This is so confusing. Again this redundant step is not part of my regular workflow I am trying to figure out why the color shift (especially one that is so pronounced) Any advise would be very welcome. thanks jeff
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