Generally, pixel values are represented by a byte (8b) after quantization. If the gray value with continuous black-gray-white changes is quantized into 256 gray levels, the gray value ranges from 0 to 255, indicating that the brightness is from dark to light, and the color in the corresponding image is from black to white. Black and white photos contain all shades of gray between black and white, with each pixel value being one of 256 shades of gray between black and white.

I divided a circle into four equal parts.
Their centers are placed at the four corners of the square.It diverges from each center point,The color gets lighter as the circle gets larger in diameter.
Simple methods can produce special patterns.
Test.