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Author Topic: Image wrecked by SRGB conversion  (Read 8327 times)
Damon Lynch
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« on: December 05, 2011, 07:04:12 PM »
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Short of actually changing the color of this woman's jacket, what is the best way to avoid the extremely poor results of converting this image from Photo RGB to SRGB? (best viewed in a web browser that handles color spaces, i.e. Firefox with color profiling enabled) –


Photo RGB image

I know it's rather average as an image, but I'm interested in how to resolve this kind of problem when I come across an image I really do care about.


Crop of Photo RGB image
http://damonlynch.net/share/20110829-1814-4-photorgb.jpg


After the conversion to SRGB
http://www.damonlynch.net/share/20110829-1814-4-srgb.jpg


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Sheldon N
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« Reply #1 on: December 05, 2011, 08:22:54 PM »
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What rendering intent did you use when converting the image to sRGB?
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Damon Lynch
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« Reply #2 on: December 05, 2011, 08:39:01 PM »
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What rendering intent did you use when converting the image to sRGB?

I used Relative Colorimetric, but none of the other three intent options appeared to make any difference to the woman's jacket.
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Schewe
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« Reply #3 on: December 05, 2011, 08:52:51 PM »
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What rendering intent did you use when converting the image to sRGB?

It doesn't matter unless you are using ICC V4 profile since color space to color space transforms only offer Relative Colorimetric (even though Photoshop allows selecting other rendering intents–which some of us have complained about for years). So going from PPRGB to sRGB will ALWAYS and only be relative colorimetric...
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Jonathan Ratzlaff
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« Reply #4 on: December 05, 2011, 10:23:26 PM »
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It looks like the red in the jacket is pretty well completely saturated; in essence it is overexposed and clipping.  That might explain the difficulty in mapping the colour to a different profile.
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Sheldon N
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« Reply #5 on: December 05, 2011, 10:31:18 PM »
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It doesn't matter unless you are using ICC V4 profile since color space to color space transforms only offer Relative Colorimetric (even though Photoshop allows selecting other rendering intents–which some of us have complained about for years). So going from PPRGB to sRGB will ALWAYS and only be relative colorimetric...

Thanks Jeff, that's good info... I had no idea that changing the rendering intent didn't work when converting between color spaces. After I posted I went and tried it on the OP's image, and they all looked equally crappy. Smiley

As far as a workaround to get the image into SRGB without it looking totally piss poor... use the Hue/Saturation tool to bring the red saturation down to a point where it's roughly within the sRGB color space, you can even layer mask off the rest of the image. Then flatten and convert to sRGB, the tonal gradation  on the coat looks much better.  It's never going to have that flaming red that you can get in ProPhoto RGB and when viewing on a wide gamut monitor, but it will look better.
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Damon Lynch
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« Reply #6 on: December 05, 2011, 10:41:00 PM »
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As far as a workaround to get the image into SRGB without it looking totally piss poor... use the Hue/Saturation tool to bring the red saturation down to a point where it's roughly within the sRGB color space, you can even layer mask off the rest of the image. Then flatten and convert to sRGB, the tonal gradation  on the coat looks much better.  It's never going to have that flaming red that you can get in ProPhoto RGB and when viewing on a wide gamut monitor, but it will look better.

Indeed! I just tried it and it worked. Thanks everyone. I would not have been able to figure that out by myself.

When I saw that woman biking down the alley, her flaming red  jacket certainly captured my attention. Unfortunately by the time I pre-focused my shot using the ground, she was aware she was going to be photographed -- hence her evasive maneuver  Wink
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Czornyj
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« Reply #7 on: December 06, 2011, 02:53:42 AM »
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You might also try excellent CIECAM02 plugin and use different perceptual correlates for image conversion:

http://sites.google.com/site/clifframes/ciecam02plugin
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FranciscoDisilvestro
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« Reply #8 on: December 06, 2011, 04:22:17 AM »
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I don´t know what software you are using, but in case you have Photoshop CS4 or newer, you could also try with the "vibrance" tool instead of saturation. This way the saturated red will be affected more, with less variation in the other colors.

Again, if using Photoshop, you could also use Softproofing, with sRGB as output color space and then turn on gamut warning. This will let you adjust vibrance or saturation just enough to avoid clipping any color.
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Steve Weldon
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« Reply #9 on: December 06, 2011, 12:26:10 PM »
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I know it's rather average as an image,

I dunno.. conversions aside.. I really like this image.   A lot.
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stefohl
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« Reply #10 on: December 07, 2011, 03:18:37 PM »
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I use a Hue/Saturation adjustment layer and reduce the saturated red colors. To restore the weaker red colors I use a Layer style in which I use a Blend if in which I exclude the strong blue and green colors in the Underlaying layer. Then the weaker red colors aren't affected by the hue/saturation layer.
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Stefan Ohlsson
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« Reply #11 on: December 07, 2011, 03:23:53 PM »
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This is how the image looks after the conversion to sRGB
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Stefan Ohlsson
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cidrmakr
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« Reply #12 on: December 07, 2011, 06:30:20 PM »
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You might try this workflow, it works just fine for me.   Raw in acr to ps at 240 or 300 ppi, prophoto, and 16 bit (which prophoto requires).  Do the work.  Duplicate the image (to save your master psd file) then on the dupe first convert to profile srgb.  then from 16 bit to 8 bit. then flatten and save as jpg.  If it doesn't go in that order you get some color shifts.
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FranciscoDisilvestro
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« Reply #13 on: December 07, 2011, 10:01:38 PM »
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You might try this workflow, it works just fine for me.   Raw in acr to ps at 240 or 300 ppi, prophoto, and 16 bit (which prophoto requires).  Do the work.  Duplicate the image (to save your master psd file) then on the dupe first convert to profile srgb.  then from 16 bit to 8 bit. then flatten and save as jpg.  If it doesn't go in that order you get some color shifts.

Your workflow will lead to the same problem the OP has. It is a problem of how to handle those colors that are out of the sRGB gamut. Since the conversion from ProPhotoRGB to sRGB is performed using relative colorimetric rendering intent, any color outside the sRGB gamut will get clipped.
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Damon Lynch
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« Reply #14 on: December 07, 2011, 11:32:33 PM »
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You might also try excellent CIECAM02 plugin

Thanks! My initial impression is that it will require some investment in simply figuring out how to use it effectively - there are plenty of options. My guess is that you believe the payoff of that time spent to be eminently worthwhile  Smiley
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Damon Lynch
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« Reply #15 on: December 07, 2011, 11:40:14 PM »
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I don´t know what software you are using, but in case you have Photoshop CS4 or newer, you could also try with the "vibrance" tool instead of saturation. This way the saturated red will be affected more, with less variation in the other colors.

I use a combination of Photoshop and Bibble Pro. I also have the Viveza 2 plugin, which is especially helpful for me because as might be pretty obvious I'm ignorant about many aspects of how to use Photoshop effectively. When I learned what the problem was, thanks to the extremely helpful responses here, I placed a Viveza control point on the woman's jacket and reduced the saturation. That solved the problem. It would be possible to add a layer and Bibble Pro and do the same thing, but it would take longer because of the need to draw an outline.

Again, if using Photoshop, you could also use Softproofing, with sRGB as output color space and then turn on gamut warning. This will let you adjust vibrance or saturation just enough to avoid clipping any color.

That's a great point. I never thought of that. I've only recently started learning about proper techniques for printing, and I have found Michael and Jeff's videos to be extremely helpful. But I didn't connect the dots between the soft proofing and web-only output.
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Damon Lynch
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« Reply #16 on: December 07, 2011, 11:41:19 PM »
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I dunno.. conversions aside.. I really like this image.   A lot.

Thanks!
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Pete Berry
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« Reply #17 on: December 08, 2011, 05:06:25 PM »
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Short of actually changing the color of this woman's jacket, what is the best way to avoid the extremely poor results of converting this image from Photo RGB to SRGB? (best viewed in a web browser that handles color spaces, i.e. Firefox with color profiling enabled) –


Damon, I may somehow be missing what you're saying here, but it seems you're blaming the conversion process to sRGB rather than the source ppRGB file - displayed here in its non-colormanaged form - for the poor result. On importing both files into CS5, they look identical, and on converting the ppRGB to sRGB, no change at all to my perception in toggling back and forth. The coat in the PP file is almost entirely OOG in gamut checking.

What application do you process in, and how did the ppRGB file look in it - surely totally different than in its display here?

Pete
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Sheldon N
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« Reply #18 on: December 08, 2011, 05:26:27 PM »
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Damon, I may somehow be missing what you're saying here, but it seems you're blaming the conversion process to sRGB rather than the source ppRGB file - displayed here in its non-colormanaged form - for the poor result. On importing both files into CS5, they look identical, and on converting the ppRGB to sRGB, no change at all to my perception in toggling back and forth. The coat in the PP file is almost entirely OOG in gamut checking.

What application do you process in, and how did the ppRGB file look in it - surely totally different than in its display here?

Pete


I'm viewing this image in Firefox (color managed) and I see a drastic difference between the ProPhoto image and the SRGB image. Both files show the same differences when viewed in Photoshop as well. When I proof the ProPhoto image into CS5, it is almost entirely within the ProPhoto gamut, no clipped red channel in the coat and very saturated reds on my profiled wide gamut monitor. If you view the ProPhoto image with softproof/gamut warning set for sRGB, then the entire coat is outside the sRGB gamut.

It is definitely the conversion process to sRGB that is crushing the out of gamut colors, I get the same results as Damon in the conversion process if I don't make any saturation changes prior to conversion.

I'm not sure what approach you're taking, but it sounds like you've got an error somewhere.
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Pete Berry
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« Reply #19 on: December 08, 2011, 09:47:17 PM »
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I'm viewing this image in Firefox (color managed) and I see a drastic difference between the ProPhoto image and the SRGB image. Both files show the same differences when viewed in Photoshop as well. When I proof the ProPhoto image into CS5, it is almost entirely within the ProPhoto gamut, no clipped red channel in the coat and very saturated reds on my profiled wide gamut monitor. If you view the ProPhoto image with softproof/gamut warning set for sRGB, then the entire coat is outside the sRGB gamut.

It is definitely the conversion process to sRGB that is crushing the out of gamut colors, I get the same results as Damon in the conversion process if I don't make any saturation changes prior to conversion.

I'm not sure what approach you're taking, but it sounds like you've got an error somewhere.

Thanks for your reply, Sheldon. The big problem is my monitor gamut, which is obviously not as wide as yours and Damon's, giving an identical view with the appearance of widely crushed reds in both. And you were right about the gamut warning being set for sRGB.

After converting to 16-bit mode and uprezzing, I printed them both on my iPF5100 through the neat little Canon 16-bit plugin. The difference is no doubt as striking as you are seeing on your monitors, with the PP image showing nice color depth, gradation and detail, with absence of the posterization seen in the sRGB image.

Pete

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