How to have a layer like 'color' in Photoshop?

Programming Questions

macko123

How to have a layer like 'color' in Photoshop?

in Programming Questions • 3 years ago

Say I have a grayscale image, and an image with just colour information. How can I overlay the coloured image onto the grayscale image, like you do in Photoshop with the layer set to 'color', and so you get one normal, coloured image. The blend() function doesn't have a colour option - is there another way to do it? The faster the better, FPS is a big concern.

Thanks.

Replies(9)

PhiLho

Re: How to have a layer like 'color' in Photoshop?

3 years ago

A way to do this is to change the alpha information of the color layer.
You can then just draw it above the gray image.

cedrickie..

Re: How to have a layer like 'color' in Photoshop?

3 years ago

i dont think thats the same effect as the color blend mode in Photoshop.
i believe you have to do it pixel by pixel.
change to HSB mode and use the brighness and saturation out of your B/W image and the HUE out of your colored image to set the pixels of your final image.

macko123

Re: Re: How to have a layer like 'color' in Photoshop?

3 years ago

That's unfortunate, I can't do that as it slows down the FPS too much.

kevin.bjo..

Re: How to have a layer like 'color' in Photoshop?

3 years ago

The highest performance will probably come from using an OpenGL filter via the GLGraphics library -- I've been thinking that converting a bunch of my old "post" and "pre" shaders from this page into GLSL would be a good weekend project (feel free to beat me to it if you're impatient :) )

Cedric, saw your recent Weave piece on "Information Aesthetics" - congrats!

kb, http://www.riftgame.com/

cedrickie..

Re: Re: How to have a layer like 'color' in Photoshop?

3 years ago

@kevin.bjorke,
thx! i just realized that they posted an article after i checked googleanalytics and wondered where all the visitors came from :)

kevin.bjo..

Re: How to have a layer like 'color' in Photoshop?

3 years ago

The little weekend project was pretty easy if you already have the code lying around.

http://forum.processing.org/#Topic/25080000000321078

kb, http://www.riftgame.com/

macko123

Re: Re: How to have a layer like 'color' in Photoshop?

3 years ago

This doesn't work either >< Well, it works, but just changing to 'GLConstants.GLGRAPHICS' in the size() function in setup halves the FPS, letalone introducing the blend modes. Might have to just stick with what I've got, or find a new way to do it entirely. Thanks anyway.

kevin.bjo..

Re: How to have a layer like 'color' in Photoshop?

3 years ago

If both CPU and GPU are too slow you may have hardware issues :)

FWIW, my version of "color" is simpler under the hood than the one suggested by Cedric: instead of using HSB mode, I just normalize the color pixels within the color cube and then scale by the grayscale value. Still has a sqrt in there but it's usually better than the three-way if() which gets used in HSB conversions (and the second one in de-conversions of the result)

kb, http://www.riftgame.com/

macko123

Re: Re: How to have a layer like 'color' in Photoshop?

3 years ago

If it was hardware that'd be fine, my computer isn't the greatest, but even on some really decent ones at uni it struggles. This is for a pretty complex music visualiser, which also has a blur function running every other frame. I need it at at least 30fps to be accurately detecting the music. Unfortunately unless I want my users to have a 12core computer I'm going to have to find another way. Thanks anyway.

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