Image to Indexed Palette PNG - Online Reduce to 256 Colors

An indexed palette PNG (also known as PNG-8) stores colors in a lookup table called a palette, containing up to 256 distinct colors. Instead of storing full RGBA values for every pixel, each pixel references an index into this palette. This dramatically reduces file size while maintaining visual quality for images with limited color ranges, such as logos, icons, illustrations, and pixel art. Our tool uses median cut color quantization to intelligently select the most representative colors for the palette.

Reducing colors offers several key benefits: (1) Smaller file sizes — indexed PNGs can be 50–80% smaller than full-color PNGs; (2) Faster web loading — smaller files mean quicker page loads and improved Core Web Vitals; (3) Game development — many game engines and retro-style projects require palette-based assets; (4) Icon and UI design — limited palettes ensure visual consistency; (5) Compatibility — some embedded systems and older software only support indexed PNG formats.

Dithering is a technique that simulates missing colors by placing pixels of existing colors in patterns, tricking the eye into seeing smoother gradients. We offer three options: Floyd-Steinberg (recommended) — produces the smoothest results for photographs and natural images using error diffusion; No Dithering — best for flat-color artwork, logos, and icons where you want crisp edges; Ordered (Bayer) — creates a distinctive retro pixel-art dithering pattern, popular for 8-bit and 16-bit game aesthetics. For most photographic images, Floyd-Steinberg yields the best visual quality.

The Median Cut algorithm is a classic color quantization method that works by repeatedly partitioning the color space: (1) All pixels are placed into a single "bucket"; (2) The bucket with the widest color range is selected; (3) It's split at the median point along its widest RGB channel; (4) This process repeats until the desired number of buckets (colors) is reached; (5) Each bucket's average color becomes a palette entry. This ensures the palette prioritizes colors that appear most frequently and cover the widest gamut, resulting in minimal perceptual loss.

Yes! Our tool fully preserves transparency. Pixels with significant transparency (alpha < 128) are kept transparent in the output. Opaque pixels are color-quantized against the palette. The resulting PNG maintains its alpha channel, making it suitable for logos, watermarks, UI elements, and any image requiring a transparent background. Note that fully transparent pixels are effectively assigned to a dedicated transparent "color slot" in the effective palette.

File size reduction varies by image content: Photographs with millions of colors typically see 40–65% reduction when reduced to 256 colors; Logos and illustrations often see 60–85% reduction as they naturally use fewer colors; Gradients and skies benefit greatly from dithering, maintaining visual quality at a fraction of the size. For example, a 2MB photo PNG can often be reduced to 400–800KB at 256 colors with Floyd-Steinberg dithering, with minimal visible quality loss.

100% free and private. All processing happens entirely in your browser using HTML5 Canvas and JavaScript. Your images are never uploaded to any server — they stay on your device. This means: instant processing without upload delays, complete privacy for sensitive images, no file size limits beyond your device's memory, and no registration or account required. You can use this tool offline once the page is loaded.