Read/Write BSDF files.

Backend Library: internal

The BSDF format enables reading and writing of image data in the BSDF serialization format. This format allows storage of images, volumes, and series thereof. Data can be of any numeric data type, and can optionally be compressed. Each image/volume can have associated meta data, which can consist of any data type supported by BSDF.

By default, image data is lazily loaded; the actual image data is not read until it is requested. This allows storing multiple images in a single file and still have fast access to individual images. Alternatively, a series of images can be read in streaming mode, reading images as they are read (e.g. from http).

BSDF is a simple generic binary format. It is easy to extend and there are standard extension definitions for 2D and 3D image data. Read more at



Whether individual images in the file can be read in random order. Defaults to True for normal files, and to False when reading from HTTP. If False, the file is read in “streaming mode”, allowing reading files as they are read, but without support for “rewinding”. Note that setting this to True when reading from HTTP, the whole file is read upon opening it (since lazy loading is not possible over HTTP).


Use 0 or “no” for no compression, 1 or “zlib” for Zlib compression (same as zip files and PNG), and 2 or “bz2” for Bz2 compression (more compact but slower). Default 1 (zlib). Note that some BSDF implementations may not support compression (e.g. JavaScript).