Role of sensor in color rendering?

Started 3 months ago | Discussions thread
57even Forum Pro • Posts: 14,505
Re: A small note...

lélé wrote:

Erik Kaffehr wrote:

I had a look at the portrait posted.

First i took two patches laid over each other with light and shadow Lab values, second I did the same but using the same L value. Here is a screen dump:

Here is the JPEG. Note how much the screen dump distorts the colors

Looking at the Hsv coordinates the hue change would be on the red/yellow segment.

Just to say, it is a nice portrait and I like the colors.

Best regards
Erik

Thanks for looking closely.

That's what Jim said (shift toward yellow).

That's what I see with the patches superimposed.
Thats' not what I see in the actual picture, at least in some areas (in paricular below the lips). It looks like the brown has 'a greenish cast'.
Some say it maybe a color contrast effects.

Human white balance issue/observer metameric failure? Possibly.

It can be extremely difficult to distinguish a greenish cast from a yellowish one.

Unfortunately, human perception isn't so straightforward with desaturated colours as it doesn't follow the same regime as saturated hues. The brain seems to adjust to desaturated colours differently - in that we are more sensitive to hue shifts than we should be based purely on retinal sensitivity. This is not accounted for by monitor calibration and it doesn't take a big deviation in the observer, or the display colour, to cause problems.

Rather than trying to balance green it sometimes helps to shift mid-yellow slightly towards red in the HSL adjustment, or try desaturating yellow slightly.

I really struggle with some colours depending on the time of day I am working on the images. I do have daylight balanced LED bulbs on my desk lamp, but colours still look slightly off compared to indirect diffuse daylight, which is a little cooler. Makes it hard to get prints right if you don't know where they will end up hanging.

A photographer friend of mine painted his entire office matt grey because anything else caused him to perceive colour shifts. Drove him nuts.

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"A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away." Antoine de Saint-Exupery

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