About anti-aliasing

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Digital images are represented by collections of small points called pixels. Therefore, you can not express finer than pixels.

Here, when drawing a circle filled with black on a small canvas of 20 * 20 pixels, it becomes as follows.

Image of the circle that was jagged
Caption. Image of the circle that was jagged

In this way, trying to represent a circle with only one color black, the circumference of the circle becomes jagged.

So let’s make this pixel “gray” because this pixel is “half covered” … this pixel is “covered by 1/4” so it is light gray, and so on … What would be the case when drawing colors with the pixel colors adjusted according to the area?

How do you change the color depth according to how much it covers?
Caption. How do you change the color depth according to how much it covers?

In this way, you can draw a much cleaner circle than the previous black one color.

Small circle anti-aliased
Caption. Small circle anti-aliased

This process is called anti-aliasing.