David J. Littleboy wrote:
"Scott W" wrote:
It should be, I use Photoshop elements, small brother to Photoshop, and there it is under the enhance menu, adjust color. You get an eye dropper that you then click on something that you know should be white in the photo.
Have you ever gotten a decent result doing that? I certainly haven't. In real life, nothing's actually white* and any daylight scene has both shadow and directly lit areas with different color temperatures.
In raw conversion, checking the overall impression by eye and looking at the readouts for areas that should be gray or white to make sure that things are reasonable is a pain, but it seems to be required.
*: I just did a test shot with three reference cards: a resolution test image printed on enhanced matte (very blue from the whiteners), a Kodak 18% gray card (roughly neutral), and a Kodak gray scale (patches of different gray levels in 1/3 stop increments) that is strongly warm toned. Not only did all three have different color temperatures, but the differences were large.
I don't have much luck with the remove color cast if the WB is off by very much and all I have to work with is a jpeg. If the color is close then the remove color cast can work ok. But I far prefer to work with the raw image, in which case the eye dropper often gets me close enough that I don't feel the need for further adjustments.
In this version of a photo I used the table cloth as my white reference, the resulting color temp comes out at 2050 and looks pretty good to my eye.
http://www.pbase.com/konascott/image/85274129 If I try to use the tea cup as a white reference I get a color temp of 1950, and the image look far to blue.
http://www.pbase.com/konascott/image/85274439 So you need a good white reference, or you need to adjust by hand.
If I try to work with a jpeg things are not as good, in this case I see the color temp at 2500, which give an image that if far too warm for my taste.
http://www.pbase.com/konascott/image/85274343 If I then use the remove color cast function, again using the tablecloth I get something that is not bad, but not as good as using the raw file.
http://www.pbase.com/konascott/image/85274345 I find the remove color cast function is only of real value if it is not making large changes in the color.
I have had pretty good using remove color cast to correct photos taken through a windshield, which have a lot of green to them.
Scott