The smallest unit of digital image is pixel. Therefore, there is no any other description except for pixel.
Let’s take this small image (20×20 pixel) for example. Then, try to draw a filled circle. Seems like the circle shown below, right?
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Image. Circle with jaggies
See!! The circle is not as pretty as imagined right. However, there is no other description other than using 1 pixel. You would like to draw a circle like this (on the left side of examples below) at first, but you are not able to make the units more smaller.
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Image. Is the only way to draw a circle in this way?
As the former image, you might think that is difference between “fill” and “unfill”.
For example, take this “covered in half” pixel, set in 50% opacity pixel. Or take this “covered in one quarter” pixel, set in 25% opacity opacity pixel. What if you adjust the opacity based on the area covered while you are drawing like this?
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Image. Opacity depends on the coverage of its part.
In this way, you can draw it perfectly by FireAlpaca.
In graphic processing, anti-aliasing performs and revised as insufficient pixels information included.
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Image. Circle proceeded with anti-aliasing