Problem with colors

[mdw]

Hi all,

I have a question about what you can see in the next 2 pictures.

First of all what is the English term for this? :oops:
For the Dutch people amongst us, I mean: "kleurenzweem". Basically there is a green overlay in the whole picture, which makes the white parts a bit greenish... :rolleyes:

Secondly, I would like to know what it causes and how you can prevent it. It'll cost you some time in Photoshop playing with curves, levels etc. to get it right...

thanks!

Not edited
http://img502.imageshack.us/img502/5635/img89252pl3.jpg

Edited
http://img241.imageshack.us/img241/1333/img8925ky7.jpg

[bbulldog]

did you shoot these in RAW? Looks like the white balance is off.

[mdw]

did you shoot these in RAW?

Yes, this was a RAW file.

[Nouks]

What were your WB settings (before and after editing)? Seems to be WB to me.

[mdw]

Hi,

Thanks for the replies!

The WB is always set to AUTO. I can't find it in the EXIF data what it is for this specific photo somehow.

thanks!

[Nouks]

Hmmm... Always greenish? Check your parameters for colour tone maybe?

[mdw]

No, but it is something you see very often in pictures. When there is a dominating color in a picture, as it is green here, you'll sometimes get an overlay throughout the whole picture. You can remove this overlay afterwards with, for example, Photoshop and levels.

[Nouks]

I know what you mean, but this shouldn't be happening and because of that I think of a setting that may be set wrong ;)

With your last post ("see very often", "you can remove this afterwards with for example") it doesn't really sound like you're looking for a fix or an explanation for this "because it can be fixed afterwards"... Thought you were trying to find a solution instead of just fixing it afterwards? ;)

WB and parameters are just two things that cross my mind because you said "basically there is a green overlay"...

English word for "kleurzweem": I'm thinking/searching ;)

[PhotosGuy]

The WB is always set to AUTO. Gray card: Why your meter may be lying to you! (http://photography-on-the.net/forum/showthread.php?t=54281)
Notice that the very last exposure in the 2nd group of tests was of a gray card.

I consider RAW to be a safety net for when you forget to set something closer.
Waiting to adjust WB after shooting RAW may be a mistake. Curtis N found that a blown red channel is a problem:
How NOT to expose to the right (http://photography-on-the.net/forum/showthread.php?t=93712)

More info on how correcting WB affects exposure levels in a bad way:
White Balance, the Secret Weapon (http://www.ppmag.com/web-exclusives/2007/11/white-balance-the-secret-weapo-1.html)

[René Damkot]

No, but it is something you see very often in pictures. When there is a dominating color in a picture, as it is green here, you'll sometimes get an overlay throughout the whole picture. You can remove this overlay afterwards with, for example, Photoshop and levels.

If you shot RAWm I'd correct it in the Raw converter, not PS proper.
The color cast (;)) is easily removable by fixing the WB.


By the way, avoid AWB like the plague. It sucks IMO.

[mdw]

Hi guys!

Thanks for the replies! I'm only shooting RAW for half a year.
I never rely looked at white balance before, and certainly didn't change it myself on the camera.

But I understand to avoid color cast (!) :D you'll need to adjust your white balance.
Could you tell me a bit more about how you deal with it?

Thanks!

[PixelMagic]

As others have pointed out your initial image has a green color cast and its quite normal. A quick Levels or Curves adjustment in Photoshop shoudl take care of the problem.

To understand why color casts occur we have to go back to first principles and recall that photography is the act of recording REFLECTED light. The green color from the leaves is being reflected on to the flowers and its also fooling the camera's sensor. Human eyes are able to automatically compensate for color casts but digital cameras cannot. As a test look at a white object under tungsten lighting, and then take a photograph of the same and look at the differences in color.

[mdw]

Thanks! Now I understand what causes color cast. Indeed, a quick levels or curves adjustment in Photoshop deals with it, but can you prevent it from happening in the first place?

[PixelMagic]

Well, you can always invest in a set of CC or color compensating filters but the simplest way to reduce the occurence of color casts is to set your camera's White Balance to the setting closest to the prevailing lighting conditions. AWB or Auto White Balance can be eaily fooled and varies too much from shot to shot, even in the same lighting, to be really effective.

Your in-camera WB setting, combined with tools like a WhiBal (http://www.pictureflow.com/products/whibal/index.html) or ExpoDisc (http://www.expoimaging.net/products/product_detail.php?prodid=2&productname=ExpoDisc_Digital_White_Balance_Filter_-_Neutral), will go a long way towards preventing and/or solving color cast problems.