[ffureel]

I am going loopy at the moment. I have this image that I have to match the colours exactly to a reference image. Easy I thought, eye picker a neutral area and a few curves adjustments and I thought that would be it. No.

Every single neutral colour I can pick in the image, (greys, whites, blacks) all have a different colour cast to them in different parts of the image. So unless I make about a million masked curves for every colour cast I am stumped.

Any ideas, I cant provide a sample, sorry.

[smiley guy]

Well... I'm just throwing ideas out there and seeing what sticks but have you tried "Match Color" in Photoshop? Maybe tweak from there once you get both images closer.

Let us know if that works.

[mistermonday]

Depending on the intensity and range of the casts, they could be easy or difficult to eliminate. Channel blending and curve adjustments can often eliminate them. Uploading an image would be more helpful.
Regards, Murray

[Flora]

Hi ffureel,

It is very difficult to answer without having a picture to work on .... maybe you could post an 'unrecognizable' cropped part of your picture ....

Anyway ... in this cases I have had satisfactory results using Selective Colors ...

Hope this helps ...

[mistermonday]

In Photoshop, a very effective way to neutralize casts is to flatten the center of the A and B curves. If the areas which contain the cast are really supposed to be neutral (black, white, or any shade of gray in between), then pulling to the zero axis, those colors on the curve which are unwanted, will return the affected areas to neutral. The trick is to make sure you lock down the curve on both sides of the the color you wish to neutralize. This is to ensure that you impact only those areas which contain the cast and not affect the other areas of the image which contain accurate color. Depending on how strong those other colors are will determine how successful this technique qill be on that particular image. However, most of the time, the cast colors occur very close to the zero axis and have values between +15 and -15.
As an example I have attached an image and deliberately inserted some small cast areas shown with arrows. The two curves show the adjustments made to the A & B channels. The last attachment is the result.

If this does not work on your image, then I would follow Flora's recommendation above.
Regards, Murray

[pure]

how can you say fast, if a picture has unbalanced colors? just slightly?

i have a picture here which looks all right. but i also learned to use the histogram and point to a medium gray in the picure (with medium pipette), then it shows the right balance. if i do this, i can click on different gray tones in the pic. and i get slithly different results.

i mean the pictures are really ok, i just want to find out how to make it perfect in the color balance.