Chroma Subsampling Explained

Compressed Digital video is used, from recording/shooting to broadcasting/ streaming. The codec’s jungle is a real source of science and can generate difficult workflow. But sometimes they can be destructive and there will be data loss we wouldn’t pick up. One of the method of data loss is the chromatic sub-sampling. Let’s see how it works.

It is known that the color of digital images is composed of 3 layers . Red, Green and Blue

A simple conversion goes from RVB in Y (luminance), U (Chrominance 1) and V (Chrominance 2). 4:4:4 – all the layers have the image resolution With 4 :4 :4 there is no sub-sampling… it happens!

4 :2 :2 Sub-sampling – the horizontal resolution of the chrominance layers is divided by 2

With 4:2:2 we reduced to 1/3 of the quantity of information to store. Naked eye cannot see/notice it.

4:2:0 Sub-sampling – the resolution of the chrominance layers is divided by 4

With 4:2:0 we reduced to 1/2 of the quantity of information to store. Naked eye cannot see it.

Little recep to understand what is going on with the first 8 pixels of an image.

Source: editfast.fr