# Pixel Art Image Converter

> Convert images into pixel art with palettes, dithering and retro effects. Resize a photo or drawing, adjust its colors, and apply an automatic or imported palette with ordered or error-diffusion dithering. Download a transparent PNG, editable pixel sprite and reusable recipe.

Part of usefulweb.site (https://usefulweb.site/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://fliplinepixelquantizer.usefulweb.site/ (interactive tool at https://fliplinepixelquantizer.usefulweb.site/tool)
- JSON API: POST https://fliplinepixelquantizer.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://fliplinepixelquantizer.usefulweb.site/api/v1/tool)
- OpenAPI: https://fliplinepixelquantizer.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://fliplinepixelquantizer.usefulweb.site/mcp - tool `flipline_pixel_quantizer`

## Inputs
- image (file, required): Image (PNG, JPEG or WebP)
- width (integer): Pixel canvas width
- height (integer): Pixel canvas height
- colors (integer): Automatic palette colors
- palette (textarea): Custom HEX, GPL or JASC-PAL palette (optional)
- alpha (integer): Alpha threshold
- scale (integer): PNG integer scale
- fit (select): Image fit
- dither (select): Dithering
- strength (number): Dither strength (%)
- brightness (number): Brightness
- contrast (number): Contrast
- gamma (number): Gamma
- saturation (number): Saturation (%)
- red (number): Red shift (RGB units)
- green (number): Green shift (RGB units)
- blue (number): Blue shift (RGB units)

## Method
- Auto-orient and convert the source to sRGB, then sample native output pixels using nearest-neighbor fit, centered fill or stretch. Images are limited to 4 MB and 2 MP.
- Apply RGB offsets, brightness and contrast, gamma, then saturation. Palette matching uses squared sRGB distance with first-entry tie-breaking. Automatic palettes select frequent adjusted colors.
- Ordered dithering uses a 4 × 4 Bayer bias. Serpentine Floyd–Steinberg distributes errors with 7/16, 3/16, 5/16 and 1/16 weights; transparent pixels neither receive nor spread errors. Strength zero equals no dithering.
- Alpha below the threshold becomes transparent. PNG integer scaling repeats pixels exactly. Dithering runs on native pixels and does not change with preview zoom or export scale.