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Problem separating color from picture

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  #1  
Old 02-24-2010, 01:32 AM
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Problem separating color from picture

This is somewhat of a technical nature...

Maybe I am too stupid or do not see the possibilities, but I have some problems simply dividing a color picture into its 2 composite parts:

1. The complete color information (that is without the greytones).
2. The complete monochrome/greyscale (contrast) information.

What I want to achieve is that these two images put together with overlaying result in the original surce (color) picture again finally.

The reason why I want to do that is, I want to modify only the color separation in a special way prior mixing all together again. (This actually could give a wide range of creativity for special modifications and some artistic expression.)

Has anyone a solution for this problem or an idea how to get these two composite image parts from any photograph?

(Well, I actually could write a programm which extracts that information from the pixel data but I want to do that with Photoshop on the fly.)

Thanks.
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Old 02-24-2010, 01:54 AM
Flashtones Flashtones is offline
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Re: Problem separating color from picture

Have you looked into lab mode?

Otherwise, in RGB, dupe your composite layer and set one to Luminosity and the other to Color.
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Old 02-24-2010, 02:11 AM
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Re: Problem separating color from picture

No I didn't look into the lab mode. Is that possible there?
RGB mode does not work the way I need it. None of the layer mode gives me a true color separation.
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Old 02-24-2010, 02:26 AM
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Re: Problem separating color from picture

With Programming you simply would do the following:

You analyze the RGB values for the lowest grey tone. I.e. The pixel value is R:170 G:54 B:69. Then the lowest greytone is logically R:54 G:54 B:54. That's the contrast or monochrome part then for the given pixel.

Then the resulting rest is the color tone, which has to be separated: R:116 G:0 B:15.
(You simply subtract the lowest grey tone from the source pixel.)

Doing that over the complete image data actually would result in one picture with the greyscale and onoter with the color tones.

Mixing it together would result in exactly the same image than the source picture.

I think this isn't possible to achieve with overlay modes. Did not find a tool also. (I tried "Selective Color" already but did not get really usefull results.)

Is there something to calculate such images in PS?

Last edited by _jason_; 02-24-2010 at 02:31 AM.
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Old 02-24-2010, 02:28 AM
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Re: Problem separating color from picture

When I need that I go for this way: create a blank layer over the one you want to separate colors from. Fill this layer with white, change the blending mode to color (is not the same of desaturating). Press CTRL+ALT+SHIFT+E to merge all in a new layer, delete the white one. Change the blending mode of the new grayscale layer to Linear Light and invert it.
At this point I don't remember (I've to try it) if it is done or if I've to change the opacity of the Linear Light one to 50%.
CTRL+ALT+SHIFT+E for the second time and delete the Linear Light layer.

So, here you have your colors information.
For reapplying the colors just put this layer in Linear Light (maybe with the 50% opacity).
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Old 02-24-2010, 02:32 AM
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Re: Problem separating color from picture

Quote:
Originally Posted by _jason_ View Post
With Programming you simply would do the following:

You analyze the RGB values for the lowest grey tone. I.e. The pixel value is R:170 G:54 B:69. Then the lowest greytone is logically R:54 G:54 B:54. That's the contrast or monochrome part then for the given pixel.

Then the resulting rest is the color tone, which has to be separated: R:116 G:0 B:15.
(You simply subtract the lowest grey tone from the source pixel.)

Doing that over the complete image data acually would result in one picture with the greyscale and onoter with the color tones.

Mixing it together would result in exactly the same image than the source picture.

I think this isn't possible to achieve with overlay modes. Did not find a tool also. (I tried "Selective Color" already but did not get any usefull results.)

Is there somethingl to calculate such images?
You can do that in Linear Light (as I described before) or by Apply Image...

With programming there's not only the way you described to calculate the monochromatic...there are many but they all works
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Old 02-24-2010, 02:35 AM
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Re: Problem separating color from picture

Thank you!

But I already did something very similar. The problem with that is, mixing it together does result in a slightly different image. The contrast information anyhow is modified. It is not exact enought.
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Old 02-24-2010, 02:39 AM
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ApWizard ApWizard is offline
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Re: Problem separating color from picture

Quote:
Originally Posted by _jason_ View Post
Thank you!

But I already did something very similar. The problem with that is, mixing it together does result in a slightly different image. The contrast information anyhow is modified. It is not exact enought.
No way!
If you do it correct there's no variation at all.
I will try with PS opened and post the right procedure asap
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Old 02-24-2010, 02:55 AM
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Re: Problem separating color from picture

Quote:
So, here you have your colors information...
For reapplying the colors just put this layer in Linear Light (maybe with the 50% opacity).
Apply on the greyscale image, right?
If I do that, I get something in middle grey mixed with the colors !?

Oh that would be nice to have! Thank you!
I was nearly at the point where I strated Microsoft Visual C++ to code the tool myself...

Jason
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Old 02-24-2010, 03:14 AM
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Re: Problem separating color from picture

I think one of my problems was, that I generated my monochrome image with desaturation. Doing such gives obviously slightly more contrast ...
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