复古抖动图片工具

Draw the uploaded image to an offscreen canvas at a chosen pixel scale and read its ImageData. For ordered dithering, add a threshold from a 4x4 or 8x8 Bayer matrix to each pixel before snapping to the nearest palette color. For error diffusion, process pixels left-to-right, snap to the nearest palette color, and distribute the quantization error to neighbors with Floyd–Steinberg or Atkinson weights. Render the result upscaled with pixelated rendering and offer palette presets as small arrays of RGB values.