avsdT:willett@avsdS.UUCP (10/12/83)
I am having some trouble in balencing and correcting color prints. Does anyone have an idea of how to calculate the correct color for a given picture? Some of the trouble I have that really is frustrating is the changing of colors in a picture due to things like the setting sun, incandecent lights, florecent lights, and such. The big question is how does Kodak or other print processors calculate the correct color when there is no obvious reference? All replys and ideas would be appreciated. Mike Willett
keesan@bbncca.ARPA (Morris Keesan) (10/14/83)
There are two standard ways for professional print processors to achieve color balance. If there is any skin in the picture, they can balance the picture so that the skin areas match their preconceived notion of what Caucasian skin looks like. More commonly, and used almost exclusively in automatic processors, I believe, they generate an average reading of the entire picture, either by "scrambling" the picture with a diffuser or by taking a reading of the whole frame with a more sophisticated color printing meter, and then print the picture on the assumption that the average picture should have an average color balance equal to an 18% gray card. If you do your own printing, one thing which can be useful is to carry an 18% gray card with you when your out shooting, and for critical shots, or when you're going to be taking a lot of shots in the same light conditions, take one shot with the gray card in the scene. Then when you're printing you can work out your balance by printing that negative, and then print the rest of the frames in that group with the same settings. You may use an occasional extra negative this way, unless you can print that negative with the gray card cropped out of the image, but film is cheap, especially compared with the amount of paper and chemicals you might otherwise use trying to find the right color balance.