PNG to PFM Converter

Encoding: the PNG uses lossless DEFLATE with a prediction filter chosen per row; PFM uses none, and the download is a 32-bit float colour PFM in linear light.

Bit depth: 1, 2, 4, 8 or 16 bits per channel in the PNG; PFM allows 32-bit floating point per channel, and the PFM written here has 32-bit float per channel. 16-bit PNGs from photo and scientific software are reduced to 8 bits per channel.

Colour: RGB, greyscale, or an indexed palette of up to 256 colours in the PNG; PFM supports RGB ('PF') or greyscale ('Pf'), in linear values, written here as linear-light RGB.

Transparency: the PNG stores it as a full alpha channel, so edges and shadows can fade smoothly; the PFM has none, so transparent areas are filled with the colour you choose.

Metadata: the PNG can carry text chunks, an ICC profile, physical resolution and EXIF in an eXIf chunk; PFM can carry none beyond the header, but nothing is copied across.

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 files usually come from screenshots, design exports, logos and web graphics.

PFM is a minimal floating-point image format in the Netpbm style: a three-line text header and raw 32-bit floats. Research code uses it for HDR images, disparity and depth maps.

A PFM file is the text 'PF' (colour) or 'Pf' (greyscale), the width and height, and a scale factor whose sign gives the byte order (negative means little-endian), then 32-bit floats with rows stored from the bottom of the image up.

PFM is the better choice for HDR research, depth and disparity maps, while PNG suits screenshots, logos, graphics and anything that needs transparency.

PFM strengths: Full 32-bit float precision; Trivial to read and write. Drawbacks to weigh: Uncompressed and very large; No alpha; Unknown to most apps.