On 28 January 2012 06:10, Martin Nordholts <enselic@xxxxxxxxx> wrote: > 2. Make GIMP clever. If GIMP encounters a tile with only values 0.0 > and 1.0, the 32 bpc data can be transparently, i.e. without the user > noticing, replaced with 1 bpc data. As soon as more bits of precision > is required to avoid loss of data, GIMP can transparently convert the > tile back to RGBA float. The same kind of optimization can be done for > completely black, white and transparent tiles too. This sounds nice, though the problem with this approach is that you need to scan each tile to work out what format it can be compressed to. It's probably quicker to work out what format the various intermediates should be in by static analysis of the pipeline of operations. For example, a threshold operation can only ever output 0 and 1 (over threshold, under threshold) so you can always have a 1-bit image coming out of it. If the next operation in the pipeline is something like dilate, which works on binary images, you can directly join the two operations up. Another useful and related optimisation is to delay the conversion from u8 to linear float as long as possible. You keep the original u8 image about plus the u8 to float LUT. For many unary pointwise operations on the image (like threshold or level adjust) you can simply manipulate the LUT and not touch the image at all. John _______________________________________________ gimp-developer-list mailing list gimp-developer-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gimp-developer-list
