PDA

View Full Version : Unwanted Color Cast - Need Help



Rex914
01-25-2005, 11:33 PM
I've been taking photos with my Kodak DC3400 for several years, and something that's kept plaguing me is its tendency to color certain objects blue. It's not exactly casting the whole picture blue, just particular things. These particular things include plates (especially china) and shadows cast by white plates among the most common.

I've tried manual white balance, but nothing seems to really help. The best solution I've found so far is just to eat a little red/yellow cast to mitigate the blue. Food looks better that way too, so a little doesn't hurt, but I rather have the photos coming out natural. Any ideas? The camera has virtually no manual controls besides white balance and exposure compensation, not even ISO sensitivity. :(

Please forigive the fuzziness of the photos. I had to reduce quality by a lot to make them downloadable.


1) Pea Shoots - See the blue in the shadows and in the leaves themselves?
2) Beef Dish - Ignoring the blown out highlights, you can see the same blue effect again.
3) Braised Brisket - Blue dish again...

erichlund
01-26-2005, 09:41 AM
I've been taking photos with my Kodak DC3400 for several years, and something that's kept plaguing me is its tendency to color certain objects blue.

I've tried manual white balance, but nothing seems to really help.
Please forigive the fuzziness of the photos. I had to reduce quality by a lot to make them downloadable.



Still, white balance is the ticket. As the photos appear cool you may be under flourescent lighting. That would be your starting point. I don't know how flexible your white balance settings are, but you may even need to go cooler than flourescent.

Color temperature is a funky thing. Reds are warm, yet their value in degrees Kelvin (K) is much lower. Blues are cool, yet have higher K values. So to set your white balance cooler, you have to set a higher K value. Seems backwards but that's because what we call warm and cool is based on emotion rather than physics.

Cheers, Eric

Rex914
01-26-2005, 04:26 PM
Unfortunately, this old camera doesn't give me the ability to set color temperatures. Are there any other ways around this?

gstafleu
01-27-2005, 11:03 AM
Are you using any kind of polarization filter? I looked at your third picture, brisket.jpg. I split the image into its R, G and B channels. The shadow on the white plate is visible in the R, faint in the G and totally absent in the B! In fact, the B values in the shadow tend to be higher (close to 255) than in the non-shadow. That is pretty weird. I'm not sure how polarization could cause this, though, but then I'm not an expert. What light are you using, it wouldn't be something weird like a mercury vapor lamp?

gstafleu
01-27-2005, 12:34 PM
As a second thought, are their any UV sources, like black lights, around?

Rex914
01-27-2005, 04:16 PM
These pictures were all taken in a standard restaurant setting. I was not using any filters or accessories as the camera has none.

dwig
01-28-2005, 09:27 AM
I've been taking photos with my Kodak DC3400 for several years, and something that's kept plaguing me is its tendency to color certain objects blue. It's not exactly casting the whole picture blue, just particular things. These particular things include plates (especially china) and shadows cast by white plates among the most common....

The pictures look like they were shot with flash and that the camera was trying, rather successfully, to balance the flash with the ambient light to create a "fill flash" situation. If this is truly the case, it is _CRITICAL_ that _ALL_ of the ambient light match the color balance of the flash. Only then, can any after-the-fact color balancing, either white balance in the cameras internal image processing or color adjustment in an image editing program, be of any use. Your pictures have all the hallmarks of flash (5000k daylight) mixed with tungsten (~2800k) or warm-white fluorescent (~3800k and pitiful CRI). The blue fill in the shadows indicates a general white balance for a warm ambient light that cast the shadow and the bluer daylight on-camera flash filled the dark shadow with its bluer light.

You must light the subject with matching color light sources first. Then adjust the camera's white balance to that one color.