Recolouring a bitmap - photographic colour temperature

[abligh]

I want to recolour a bitmap - specifically what I'm trying to do is the sort of thing you'd normally do in photoshop - attach a face from one picture to a body in another picture. If the lighting conditions in the two photos are similar, this seems to work pretty well, by cutting out the face from the second picture, superimposing it on the first, and feathering. If there's a slight variation in lighting conditions, you can get around this with a similarly shaped and feathered overlay, with a flat colour and transparency applied to it such as "darken", or "saturation". However, what I'm having difficulty with is adjusting colour temperature. Differences in indoor vs. outdoor lighting etc. seem to make hue adjustment very hard. Is there any easy way to do this I've missed? I can't seem to get it to do much sensible either in Xtreme (through various uses of transparency) or XPE. I'm not a Photoshop wizard so I don't know if it's easier there.

[Soquili]

Hi Alex,

I've had some success using transparencies similar to using colour correction filters on a camera. I've found that Bleach and Hue transparencies seem to work best for correcting colour temperature.

The attached file contains a photo that was post in the Photoshop forum. The effect can adjusted by changing the colour and/or transparency.

If I were at home I could have used a tungston tinted image to show the effect more dramatically.

[abligh]

Hi Alex,

I've had some success using transparencies similar to using colour correction filters on a camera. I've found that Bleach and Hue transparencies seem to work best for correcting colour temperature.

The attached file contains a photo that was post in the Photoshop forum. The effect can adjusted by changing the colour and/or transparency.

If I were at home I could have used a tungston tinted image to show the effect more dramatically.

Yep I've tried that. The kind of problem I see is where you've got (say) red in the darker areas, and you want it to go (say) brown, yellow overexposure for flash that needs to go white etc. I've tried taking the whole thing back to contone then recolouring manually from there but with relatively little success.

Alex

[gnurf]

Say hello to Sean Moore, or is it Roger Connery!

This is what I came up with after some fiddling... I try to explain it a bit closer in a day or two if you want to (I'm in a bit of a hurry right now)

I put the original xar-file for your investigation.

[-=Drifter=-]

Very nicely done, Paul. I took it apart and saw some smaller heads under the new larger one... wasn't sure what they were for.

[parahandy]

Bob check out Enhance function on plugins used in conjuction with cutting out part of image, you can do some changing with that, make skin tones lighter or darker redder etc. I just found this out for myself.

[Mike Bailey]

Whenever I transplant a head they always end up with some goofy expression.

[gnurf]

Bob - The "smaller heads" are just working copies. The interresting part is the C,M,Y and K layers where I simulate color correction with darken/lighten transparencies. If a image is too cold/blue you need to either remove blue or add yellow etc. The rule of thumb is RGB-CMY(K) color ballance: Increase red and cyan will decrease. and vice versa. Increase green and magenta will decrease, increase yellow and blue will decrease.
More rules of thumb: Neutral skin color is about 15% cyan, 28% magenta and 30% yellow, or in other words magenta about 2x cyan, and slightly more yellow than magenta. And this is the skin color of "pale faces".African and Asian skin color have different values.

[parahandy]

hi gnurf can you do what you do with an old black and white image as I can do in PSP that would be of interst to us.

Norman.

[gnurf]

Yes, Norman, I can - I don't know what you do to your black&white images in PSP, but I guess I can do it if you tell me what you do