PBM to PNG Converter

Encoding: the PBM uses none, but 8 pixels are packed into each byte; PNG uses lossless DEFLATE with a prediction filter chosen per row, and the download is a lossless 8-bit PNG with full alpha.

Bit depth: 1 bit per pixel in the PBM; PNG allows 1, 2, 4, 8 or 16 bits per channel, and the PNG written here has 8 bits per channel.

Colour: black and white only in the PBM; PNG supports RGB, greyscale, or an indexed palette of up to 256 colours, written here as 8-bit sRGB.

Metadata: the PBM can carry only comment lines in the header; PNG can carry text chunks, an ICC profile, physical resolution and EXIF in an eXIf chunk, but nothing is copied across.

PBM stores 1-bit black and white images, used for fax-style documents, plotters and bitmap fonts.

A binary PBM starts with 'P4', the width and height, then the pixels packed eight to a byte, where 1 means black. The plain 'P1' variant writes 0s and 1s as text.

PBM files usually come from document scanning, fax pipelines, OCR preprocessing and bitmap fonts.

PNG stores pixels losslessly with full alpha transparency. It is ideal for screenshots, logos, UI and anything with sharp edges, but photos saved as PNG are several times larger than JPEG.

A PNG opens with an 8-byte signature and is a chain of chunks, each with its own CRC: IHDR (size, depth, colour type), optional PLTE and tRNS for palettes, one or more IDAT chunks with the compressed rows, and IEND.

PNG is the better choice for screenshots, logos, graphics and anything that needs transparency, while PBM suits 1-bit bitmaps.

PNG strengths: Lossless: no quality loss, ever; Full transparency with smooth edges; Perfect for text, screenshots and graphics. Drawbacks to weigh: Large files for photographs; No standard animation (that is APNG).