On Sat, Oct 4, 2014 at 2:46 PM, Elle Stone <ellestone@xxxxxxxxxxxxxxxxxxxx> wrote: > Based on the groundless premise that editing operations should produce the > same results when performed on the same colorimetric colors, .. No; but same parameters for same input colors producing same results is considered desirable behavior. Predictable interfaces are nice interfaces. > ... the BABL/GEGL/GIMP architecture specifies that: > > 1. sRGB should be the universal RGB working space. No.. but GEGL stores the pixel-format/color-space of a pixels values along with the pixel as it is passed around (along with the whole GeglBuffer actually). Internally GEGL doesn't use ICC for this but BablFormats which represents a subset of possible ICC formats. The "profile connection space" used by babl is linear RGB with sRGB primaries, since this permits very low overhead for doing operations in this color space; a color space which also is suitable for these operations (most layer compositing modes and blurring). The intention is to keep using babl for internal buffer management and integrate well with an external color management system for interacting with the more complex things ICC profiles express. > 2. Developers should decide whether an operation is done using linear RGB or > RGB encoded using the "almost perceptually uniform" sRGB TRC. Almost, developers decide which pixelformat is appropriate for their operation, with a choice of linear RGB, sRGB, CIE Lab, some gray scale formats as well as formats used with digital video with different data types; currently the set of babl formats. The problems you've pointed out with for instance multiply have led to a consensus that we will also need a target-space/working-space choice, perhaps two; one linear and one more perceptual. The logic involved in configuring the pixel format inputs/outputs of each operation could possibly be made more configurable (in GEGL, not necessarily work to be done by the implementor of the op), thus also enabling mostly conversion free processing modes of operation like what you seem to want when you reduce babl to only deal with precision conversion. /pippin _______________________________________________ gegl-developer-list mailing list List address: gegl-developer-list@xxxxxxxxx List membership: https://mail.gnome.org/mailman/listinfo/gegl-developer-list
