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I'm seeing a strange colour shift in the shadow...


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Hi all,

 

I'm in the process of correcting a shoot, and I'm having a funny problem. In the shadow side of my subject

I'm seeing a strange shift in colour. It actually is going from a red shift in the darker regions to a cyan shift

in a band at the edge of the shadow. There's actually a noticeable line between the two. I'm including a

copy of the imgae, although I find the shift to be more subtle on my screen than it is in print. Not sure

how much you'll be able to see...(and before anyone asks, I do have a calibrated monitor)

 

Does this sound familiar to anyone? Any ideas on how to correct this?<div>00H712-30868584.jpg.d4d707ee28db9bed06decb22b8c71eba.jpg</div>

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I really can't see any shifts on this small image, but no color film has perfect crossover characteristics.

Ektachrome goes blue, Portra 160VC goes brown, Kodachrome goes all over the place. They all have their unique charm

 

But again, I can't see anything on this small image, so I could be wrong, you could be having an issue there..

 

Could you post a crop of the problematic region?

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Heh.... I guess I neglected to mention I'm shooting with a digi (Canon 10D). The image I've

posted is what I get after my RAW conversion and white balancing. Here's a crop of the area

affected in specific.<div>00H72v-30868784.jpg.9ff80d7bc27205ee41229d4e587a5ab6.jpg</div>

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I see it now, but it's very subtle, personally I wouldn't change anything.

 

Cyan and red are oposite colors, so both casts are caused by very subtle "bumps" in the red curve.

If this bothers you, you'd have to locate those tones on the curve and tweak the curve by slightly increasing the red gamma around that area of the brightness range (a very localised adjustment) but limit it around that range only so you don't screw up the crossover of the remaining part of the range.

 

Why increase? Because the darker part is a bit redish while the brighter part is cyanish, which means you have more red in shadows then neutrality would demand and less red in that part of midtones than neutrality would demant, which means the local gamma of red has a "bump", being slightly less steep than the rest of the red curve, which would need to be corrected.

 

But really I can barely see it

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Thanks Edgar... I'll give that a try. I had been attempting to remove the cyan until this point,

with little results. I noticed the red shift on closer inspection of my print today. I had been

wondering if it was something along those lines. To be honest, I was a little worried that

there was something inherently wrong with my image in the first place....hence why I posted

it to see what the thoughts were...

 

Actually, given the reaction I think perhaps my husband is right.... he rolled his eyes when I

started talking about my theories on what was happening and groaned "oh god... you're not

still nit picking about those photos are you?". ;)

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Hi Amber, your colors look fine to me. I'm not sure what ISO you shot at but if possible always use the lowest your camera has because sometimes you can get funky colors from digital noise in areas of the shot that weren't exposed to much light - especially at high ISO values. I don't think what you're seeing will be a problem in a print but you can always print one and try it out.
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Beau- I almost always shoot at 100 iso... :)

 

The problem I'm experiencing is almost exclusively visible in the prints. I find I can see it

slightly on my monitor, but the difference in colour on paper is much more prominent.

 

These are prints that I'm having done at my lab btw. They're one of the best colour managed

labs in town, but I'm begining to wonder if it's more a limitation of their printer.

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