Why does compressing an image or GIF create noise in previously-solid areas? Surely that requires MORE information to be stored?
In: Technology
I believe it partly has to do with the color depth. Every image has a certain set of colors it uses.
Unless the image was created on a computer, it is very very unlikely that an area really is a solid color.
Think of these areas like a color gradient. Eg. going from red to blue. Now obviously, in the center, you’d have many pixels that are purple, because of the color mixing. So to reduce the overall amount of information that needs to be stored in the file, you just use the two colors – red and blue – and for blending them together, just use a checker pattern and vary the density of the colors fields/pixels.
Like this: xxxxxoxxxxooxxxoooxxooooxooooo
Overall it looks noisier, but the amount of colors is drastically reduced.
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