Overview

MuPDF can optionally make use of a color management engine to offer a fully color managed workflow.

Its use of the engine is encapsulated within the fz_cmm_engine structure. Currently we provide an implementation of this structure using a modified version of LCMS2 (known as LCMS2MT), but systems with other CMM engines in already can use those instead by reimplementing the functions therein.

By default, on start-up, MuPDF has no color management engine enabled. This keeps the library size down (and performance up!) for people who do not wish to use it.

/*
   fz_set_cmm_engine: Set the color management engine to
   be used. This should only ever be called on the "base"
   context before cloning it, and before opening any files.

   Attempting to change the engine in use once a file has
   been opened, or to use different color management engine
   for the same file in different threads will lead to
   undefined behaviour, including crashing.

   Using different ICC engines for different files using
   different sets of fz_contexts should theoretically be
   possible.
*/
void fz_set_cmm_engine(fz_context *ctx, const fz_cmm_engine *engine);

/*
   Currently we only provide a single color management
   engine, based on a (modified) LCMS2.

   An unmodified LCMS2 should work too, but only when restricted
   to a single thread.
*/
extern fz_cmm_engine fz_cmm_engine_lcms;

fz_set_cmm_engine(ctx, &fz_cmm_engine_lcms);

It is possible to switch between ICC and non-ICC workflows in the same instance of MuPDF (and even to use the two simultaneously). It is, however, not generally possible to swap a given context once operations on that context have started. This is because any outstanding fz_colorspaces (such as those found within the store) will still refer to the wrong color management implementation!

30.1 Overview