Dither and banding for image processing

Since the previous article involves these two concepts, and I have no idea about image processing, I wrote an article dedicated to understanding these two concepts.

Colour banding

Banding is an issue of inaccurate Color Representation in computer graphics.

Dither

Dither (jitter) is a type of intentional noise that is used to randomize the quantization error and prevent problems such as banding when images are greatly pulled up. dither is often used in digital sound and digital video data processing, and compact disc.

Dither Source:
It originated from World War II, when bomber pilots used a mechanical computer for navigation and bomb orbital computing. The strange thing is that these computers (consisting of hundreds of mechanical parts) are more accurate on the plane deck than on the ground. Engineers realized that the plane's vibration reduced the errors caused by some of its moving components. To make them work better, engineers have installed vibration motors for such computers. They have shaken these Motors into dither .......

Dithering in image processing is a technology that creates the illusion of color depth in Images Using a finite color palette. In a dithered image, the colors that are unavailable in the palette can be replaced by an approximation of the colors available in the current palette. human eyes can accept this mixed color composed of colors. Dithering is similar to the halftone printing used in printing technology. Dithered images, especially with a few colors, usually show the particles contained in the image. (I feel that I cannot understand the translation. Directly :)

An authentication of dithering. Red and blue are the only colors used but, as the red and blue squares are made smaller, the patch appears violet.

Dithering technology was used in early video adapters, LCD on some mobile phones, and some cheap digital cameras, the color gamut of these devices must be smaller than those of more advanced devices. For example, a photo image may contain millions of colors, but only 256 colors are supported on the video hardware. Therefore, you need to use these 256 colors to achieve the same effect as the original image through dither technology. If dithering technology is not used, the unsupported colors in the source image may be replaced by the approximate colors of these colors, which will lead to poor display.
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In addition, the use of dithering is a factor limiting the format of image files. In particular, the GIF is usually strictly limited to 256 or less colors (in most image editing software ). Other formats, such as PNG, are restricted to reduce the file size. These pictures with restricted colors contain a color palette of the colors they use. In this case, the image editing software is responsible for dithering images, not just for storing such files in these formats.

Algorithm:
There are many dithering algorithms. One of the earliest and still popular ones is Floyd-steberger dithering. (there are also many algorithms that are introduced on Wikipedia)