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Author Topic: Out of gamut colors and color shift  (Read 925 times)
Alex MacPherson
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« on: January 15, 2011, 12:29:47 AM »
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I recently did a shoot that had quite saturated colors in it. I am preparing the final files for srgb jpg print files.

Because of the color saturation in several of the images, I check the gamut warning and have seen that there are some problem spots.

I am pretty new to using this feature of PS so I have some questions.

1. When you get a gamut warning in a dark spot of the image... does it just mean it will print as pure black?

2. Does a gamut warning in a saturated color mean it shift color when it prints?

The reason I ask is that I did a soft proof on an unmodified jpg and noticed the lips went from a fuscia color to burgundy.

Is there a way to prevent the color shift and keep nice saturation?
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Alex MacPherson

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stefohl
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« Reply #1 on: January 15, 2011, 04:44:19 AM »
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The gamut warning is a problematic feature in Photoshop. Today, with our monitors with a colour gamut bigger than what is printable, I prefer to just see if there are colour shifts when I softproof. But as you have noticed, there are colours that can shift in hue when they are converted. There are also colours that can loose their separation when you convert to a smaller gamut. I use a Hue/saturation adjustment layer to correct this when I'm softproofing. If there is a colour shift I use the hue, if there are colours that go flat I reduce the saturation.

As this affects all the colours in the selected range, I use a layer style to restrict the change only to the most saturated colours. If the troublesome colour is a saturated red, I change the green and blue channels as I have shown below.

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Stefan Ohlsson
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Alex MacPherson
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« Reply #2 on: January 15, 2011, 03:06:49 PM »
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I downloaded the ICC profile from the local printer I am going to use. I want to make sure that I am doing the right thing.
Here is what i have tried:

I have noticed a problem with red shifting hue.

I duplicated the image so that I could view the original and compare it to the proof.

With the duplicate. I went to the menu view> proof setup>custom> selected the ICC i downloaded from my local printing company.

This makes the image on the screen show the proof colors.

I then went into the hue/saturation and adjusted the shifted colors until they look close to the colors of the original.
However, when I turn off the proof colors and just look at it in sRGB , the reds look oversaturated.

I am not sure I am doing this right.

Will it print correctly for the reds?
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Alex MacPherson

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digitaldog
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« Reply #3 on: January 15, 2011, 03:12:41 PM »
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I am not sure I am doing this right.

Will it print correctly for the reds?

Yes you did this correctly (hopefully on an adjustment layer). Will it print correctly? Depends on the profile and how the lab will or will not use it. If they let YOU convert (pick rendering intent, CMM, Black Point Compensation) AND the profile reflects the print conditions used AND your display is properly calibrated and profile, it will print correctly for the reds. If they demand you send them sRGB, we have no idea what conversion process will be used so the answer is, maybe.
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Andrew Rodney
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Alex MacPherson
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« Reply #4 on: January 15, 2011, 03:20:58 PM »
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Thanks. I guess the next step is to do a test print from them and see what I get.

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Alex MacPherson

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Coloreason
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« Reply #5 on: January 15, 2011, 10:45:15 PM »
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I downloaded the ICC profile from the local printer I am going to use. I want to make sure that I am doing the right thing.
Here is what i have tried:

I have noticed a problem with red shifting hue.

I duplicated the image so that I could view the original and compare it to the proof.

With the duplicate. I went to the menu view> proof setup>custom> selected the ICC i downloaded from my local printing company.

This makes the image on the screen show the proof colors.

I then went into the hue/saturation and adjusted the shifted colors until they look close to the colors of the original.
However, when I turn off the proof colors and just look at it in sRGB , the reds look oversaturated.

I am not sure I am doing this right.

Will it print correctly for the reds?
I'm no expert, but from what I've learned I think you should use Edit > Convert to Profile to convert the image to the printer profile. The color management will change the color values accordingly while trying to preserve the look as much as possible.
If I understand correctly what you did is a manual color correction as an alternative to what color management is suppose to do automatically by Convert to Profile. Of course you can do both, Convert and if necessary still color correct manually.
When you color edit only based on Soft Proofing, you should also make sure that the color values are not further altered by color management and send the file untagged to the target device. This is because soft proofing simulates how the current pixel values like RGB will be reproduced on the target (in your case - printer).
Alternatively to soft proofing and sending untagged image, you can choose Edit > Assign the printer profile to the image and while the pixel values won't change, they will be displayed the same as if using soft proofing with the printer profile.

As digitaldog already suggested, if you and the lab don't work in accordance with each other regarding color management nothing can be predictable
I hope this helps and doesn't confuse you. Grin
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