APNG to BMP Converter

Encoding: the APNG uses lossless DEFLATE per frame, like PNG; BMP uses usually none; RLE for some 4 and 8-bit files, and the download is an uncompressed 24-bit BMP, or 32-bit with alpha when the image has transparency.

Bit depth: 8 bits per channel in the APNG; BMP allows 1, 4, 8, 16, 24 or 32 bits per pixel, and the BMP written here has 24 or 32 bits per pixel.

Colour: RGB or an indexed palette in the APNG; BMP supports RGB or an indexed palette, written here as 8-bit sRGB.

Transparency: the APNG stores it as full alpha on every frame; the BMP keeps it as an optional fourth byte in 32-bit files, which many programs ignore.

Animation: fcTL frame-control chunks with fdAT frame data after the first image; the BMP holds one image, so only the first frame is converted.

Metadata: the APNG can carry the same text and ICC chunks as PNG; BMP can carry nothing beyond the header's resolution fields (and a colour profile in rare V5 headers), but nothing is copied across.

APNG extends PNG with animation frames. Unlike GIF it keeps full 24-bit colour and smooth 8-bit transparency, at the cost of larger files.

An APNG is a valid PNG with an acTL chunk announcing the frame count and loop count; each later frame is an fcTL chunk (size, offset, delay, blend and dispose rules) followed by fdAT data. Software that does not know APNG simply shows the first frame.

APNG files usually come from animated stickers (LINE and Discord among others), UI animations and Firefox-era web graphics.

BMP stores raw, uncompressed pixels. Files are huge but trivially simple, which is why some legacy Windows software, embedded displays and printers still ask for it.

A BMP is a 14-byte file header ('BM' and the offset to the pixels), a DIB header (40 bytes, or 108 and 124 bytes in the V4 and V5 versions that add colour masks and alpha), an optional palette, then pixel rows padded to 4 bytes and normally stored bottom-up.

BMP is the better choice for legacy software and embedded systems that require it, while APNG suits high quality animated stickers and UI animations.

BMP strengths: No compression artifacts; Read by very old and very simple software. Drawbacks to weigh: Enormous files; Poor support for transparency; No metadata.