portable float map (picture format) (PFM)

Portable Float Map (PFM) is a file format for HDR photos, i.e. photos with an extremely large dynamic range and high brilliance. Besides this file format, there are two other formats for High Dynamic Range Images( HDRI), RGBE and XYZE.

The PFM file format is based on the Netpbm format, with which it shares some similarities. However, it is inconsistent with the Netpbm formats. It consists of a byte stream made up of a header followed by a raster. The values transmitted in the stream refer to the pixels, their width, height and aspect ratio. The pixel data is specified as a floating point number from the aspect ratio.

The PFM header consists of three consecutive ASCII lines. Each line is followed by a white spacecharacter that identifies the next line. The following grid represents the pixel sequence, with pixels following each other sequentially. In lines from left to right and in frames from bottom to top. Each pixel consists of one or three samples. One sample applies to gray tone, three to color representations.