What you really need to know about colors and color-checker !

Image representing Adobe Systems as depicted i...
Image via CrunchBase

Yesterday I have posted an article about colors, calibration of displays and the color-checker.
Today I want to go deeper into this subject.

Bildschirmfoto 2013-08-13 um 18.46.12

What are steps that the light goes thru when you shoot digital? We really have to understand that so we can figure out what to do get the real colors.

Step one is what I see. White is not white (same thing applies for other colors). White is white in a specific so-called white balance. My wife wears a white T-shirt on the beach. It’s white. OK ? Then we go in a night club, Her T-shirt is still the same, everyone will say she wears a white T-Shirt. But the white on the beach and the white in a club are different. This is the White Balance Effect. The good thing is that the WB influence the entire color range in the same direction. So our brain, somehow corrects the balance. We all have experienced it : you are in a bar with red-ish lights and you go out : your first impression is that the light has a blue hue outside. After a while, you do not notice it anymore, your brain presses the button “WB-Correction” and everything looks normal. But the light hasn’t change.

So, how it is with camera ?

Step two is the light captured by the lens. It goes actually thru a bunch of glass pieces and each of them influence the quality of the light (amount of light, which means contrasts and colors). According to this statement, every lens has its own “lightprint”. Keep that in mind for later.

Step three is the sensor. Depending on the technology used, the sensor analyzes the light, pixel after pixel, and translates it into a value which contains information about color, brightness, etc…

English: A bayer pattern on a sensor in isomet...
English: A bayer pattern on a sensor in isometric perspective/projection (Photo credit: Wikipedia)

Step four happens after you have uploaded your pictures from the cam. Lightroom, but other softwares work the same way, reads the files and has to translate these into a picture on a screen. This translation is a program that says “for such a value, the pixel has to look like this !” and this, pixel after pixel. This translator has a name. It is called PROFILE. So, there are many ways to write translators, wich means there many way to translate the data and to provide an image. LR has a buit-in Profile called ADOBE PROFILE. It gives good results in most of the case. But still, it is not perfect. Your CAMERA PROFILE is also on board so to say, and this one is very interesting since it shows you how your camera sees the world. Then switch to ADOBE PROFILE, you see how ADOBE sees the world, trying to guess how to correct step 1, 2 and 3.

Now let’s have a look at the shots I have posted yesterday.

My model wanted to have a great shot of her wrapped in her scarf. She loves the violet colors and the green reflections. I make a shot, and the picture is very different on the camera display! Why? Well, the profile used is the camera’s profile + the RAW (NEF) file is converted into a jpeg. This compression creates data loss. OK, I upload the files in my PC and this is how the picture looks like with the CAMERA PROFILE:

Bildschirmfoto 2013-08-13 um 18.44.23

And here, you can see how the ADOBE PROFILE translates the data of the file to create the picture:

Bildschirmfoto 2013-08-13 um 18.44.03

In both case the image is nice, but the colors are not what they should be. The skin is OK, but the scarf is way too blue.

Now, you can think: “maybe it is because my screen is not calibrated.” And you are right, you have to calibrate it too make sure that what you see is what other guys with a calibrated screen also see like you do. So I calibrated my Imac, I have noticed a few changes, but the bluish hue remained.

And this why a color-checker is very important: it creates a profile for the pictures you are doing right now. The color-checker pass is a software which aims is to recognize colors on a picture. Besides, you have a sort of passport with several rows of different squares of color. The software knows how these colors are in the file and compares with how they should be. Then it computes the adjustments and creates a new profile you have to name before using it.

So, during my shooting, I make a shot with the opened passport that lightroom is able to recognize. It asks me to name this new profile and it’s done. I can synchronize the other images of this very one shooting set up and that’s it.

And the scarf had the nice violet / green colors back.

Have a look:

Bildschirmfoto 2013-08-13 um 18.44.42

I have chosen a RAW file so you are positive there is no photoshop done here.

More to come…

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