I have a lot of digital photos of art objects to process. They are all
taken under identical light conditions and camera settings and with
the identical neutral gray background.
But the color and brightness of the background in the shots changes a
lot depending upon depending the overall brightness and colors of the
object being photographed.
Nothing I have figured out how to do with the camera -- a Nikon
CoolPix 950 -- seems to get around this effect. It is like the camera
is just deciding to "improve" each shot by compensating the background
to balance brightness and color of the object.
For a while I used the method of making a reference point in the gray
background and calculating the average of the red, green, and blue and
then using curves to set each of the inputs to output the average.
But some of the backgrounds were still darker and some lighter.
Then I just started to do this:
1. Put a number like 140 or 150 onto the clip board.
2. Hit control-M to open a curves adjustment.
3. With shift and control held down, click on a part of the image that
should be neutral gray.
4. With control down, hit 1 and then double click in the output box
and hit v.
5. Do the same thing with 2 and 3 to set the other channels.
The result is a uniform neutral background that does not seem to
distort the colors of the object.
1. Why should this be necessary? Shouldn't there be a way to tell a
fancy camera like the Nikon CoolPix 950 to shoot in a way that gray is
gray? If so how? I can't find a way.
2. Given the problem, and the need for uniform gray backgrounds in the
result, is the above the best way to go so far as keeping the colors
of the objects undistorted?