Recolouring a bitmap - photographic colour temperature

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.

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.

Quote:

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Originally Posted by 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.

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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

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.

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.

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.

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

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.

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.

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 :)

He colored one in another thread:
http://www.talkgraphics.com/showthre...eferrerid=9056

Well gnurf take an old photograph that has no co;our and give the face flesh tones and the clothing some colour as well like I did with this picture of my dad or that picture in the thread as Bob pointed out . Thank you.

Ok, finally had the time to colorize a bw-photo with Xara. I usually use Photoshop with the Color layer mode. Now I used layers with Stained glass (quite eqvivalent to Multiply layer mode in PS) and Bleach (Screen layer mode in PS). A lot of transparency percentage adjusting, as well as using feathering on the shapes. I attached the Xar-file so you can rip it apart :)

Simply put: find the color you wish to use and adjust the saturation/brightness with transparency percentage if it appear too bright. Also, you have to add shades so for example faces do not look flat (look at the cheeks, chin and forehead in my example). And you will notice it is mostly about very subtle tones and adjustments, but they will make a very big impact on the final work!

And a final note; don't use pure black or pure white in your images! A very common mistake (even among so called professionals) is to use pure white on eyes and teeth. I usually use a shade of blue on eyes and a shade of yellow on teeth. In the colorized version converted my "black&white" RGB scan to grayscale by right-clicking on 90% black (instead of 100% black) to preserve details and avoid making the photo too dark.

Norm and Paul - both are excellent examples of what can be done to color b/w photos. Great jobs. [Norm, apparently your dad was the last one in the ancestral line to be a handsome gentleman.... :p ]

Thank you Paul, I had an idea at the back of my head that that would be the path to take you certainly made a very fine job with your photograph.

Norman

(with apologies for answering my own question)

Hue Transparency seems to be quite useful.

Alex