Color calibration for dummies (without the maths)

[vbs (Bojidar Bojkov)]

@Tamas_Papp

You will never have an “universal” correction profile, for the following reason: every pixel recorded on your camera sensor will have a value

I am not sure I can quite agree with this.
For simplicity - I am going to ignore the math. Reason - I can’t even pretend to understand it - so commenting on it is not possible for me. So - I will stick to what I can see.

@Tamas_Papp

Make sure that your monitor has decent colors, ideally calibrated,

I agree - the best that we can do is calibrate. If we don’t we are leaving it at the mercy of the default profile and the manufacturer’s settings.

@Tamas_Papp

Forget the color checker unless you are especially required to match exact colors (eg product photography or similar). It is impractical and unnecessary for a hobbyist, and most color checkers have colors well inside the gamut.

I don’t understand why.

The following is not processed (except the default enabled profiles). The only difference is

• left - calibration with color checker and left with “as shot in camera”

• right - no modifications done - no color checker used but left again with “as shot in camera”

It is completely debatable what is better - left or right but the point that I am trying to make is that they are different.

What @s7habo shows is a creative use for the colors. The camera calibration is just a tool - a starting point. It is never meant to replace the creativity.

@Tamas_Papp

Learn to use color calibration and its cousin rgb primaries, and fine tune with color balance rgb. Try one instance for practice, but accept the fact that in the general case, you will not be able to correct the colors with just one instance of any of these modules (you need to explicitly or implicitly mask areas, eg using color balance rgb). Practice. It may take hours of fiddling on one photo, but it will be faster for the next, and even faster afterwards.

There was an interesting discussion with examples here

Introducing "primaries" feature for sigmoid

I recently had a photo assignment where my task was to document one union campaign photographically. The union members were all wearing different safety vests. While editing photos, I realized that the orange vests were very difficult to process with sigmiod options alone. Here is an example. At first I had to underexpose the shots a lot because orange vests threatened to break the gamut limit: [grafik] When increasing the exposure with exposure module and increasing the contrast in sigmoid…

And specifically the challenge that @s7habo had to deal with - specifically big amount of pictures.

I am often facing a similar challenge. Big amount of pictures (family photos) and I am trying to process them with minimum amount of masking. If I must use some - I try to stick with parametric only.

Introducing "primaries" feature for sigmoid

This is nice and the masking functions of darktable are also excellent, but if I have to process about 100 out of 300 photo shoots for the customer, then I would like to do it without the elaborate masking as far as possible in order to be able to work efficiently. [grafik] The addition of primaries to the Sigmoid module has made this work much easier for us event photographers, as we often have to deal with unfavorable lighting conditions. This was also very nicely demonstrated above by @fla…

@Tamas_Papp

Learn to use presets, save and reuse various corrections, especially for a batch of photos taken under similar conditions.

This is where the “universal” profile comes to play. I find it helpful to have a bit better starting point and then build on it. Sometimes I build more because I like the picture that I am working on and other times I build less - when the picture is more of a good memory but not necessarily something that has significance in somebody else’s eyes except myself and my family.

Finally - can we go without the color checker - yes - most of us have done it for years.

Should we ignore it / not consider it etc.? It depends on the case and on the photographer. I wouldn’t “ignore” it but there are times where I would consider it more than others. Frankly - it is a newer addition for me so me exposure to it is limited. Probably I wouldn’t have bought it except it was on sale.

Is the experience better with it? I think so, I hope so. Ask me again in a few years