чт, 4 авг. 2022 г., 14:36 Andrew Randrianasulu <[email protected]>:
> https://ninedegreesbelow.com/photography/lcms2-unbounded-mode.html > > > It seems not all icc profiles are the same ... > > > I think for cin-gg it makes sense converting from biggest rgba-float (32 > bit floating point value per color channel) , and for CVE from 16 > bit/channel int format .... (I think back in time Adam deleted int 16 > formats from Cinelerra 2.0 as opposed to cin 1.2 saying they were not as > good as true 32 fp) > > I put some emphasis on opengl output because it offloads some of per-pixel > math to graphics hw, but slower sw only mode probably will work as proof of > concept. > > As far as I understand you even can have colord daemon monitoring > hot-plugged output devices incl. monitors and providing associated profile > via some api (?) yet I only compiled it and newer used ... > > It seems at least two display pathes needed, one for traditional 8 bit > displays and another for newer 10 bit ones. i thought because color > profiles known and used ever since 1996 or so, 8 bit output can be done > first .. > > I'll try to find simpler lcms2 examples ... > Does this example count as useful tutorial? https://stackoverflow.com/questions/22561176/lcms2-convert-cmyk-to-rgb-through-profiles-in-c-help-on-input-output-values It uses rgb to cmyk and two profiles, but hopefully one just can call this with one real and one built-in profile? It was nice to know you can do scanlines with lcms, too .... I also was reading ninedegreesbelow.com articles on color spaces and it seems some of our trouble with blend modes with text and fades caused by (missing?) linearization, see https://ninedegreesbelow.com/photography/test-for-linear-processing.html I did some hack for normal blend mode using code from stackoverflow and code posted in our bugzilla See https://www.cinelerra-gg.org/bugtracker/view.php?id=559 So, in theory this (fast) linearization step should be added to all modes, or at image-reading stage only? Also, good way to put lcms transform code in our rgb2rgb function (somewhere in guicast? ..but in cingg some of this code python-generated and I do not know python at all ..), just with additional parameters like pointer to in and out profiles? If any of them null then just not execute transform call ... > Adding profile to some video container hopefully will be not very hard > task (i forgot about this patch for ffmpeg's mov muxer from 2019 i talked > about in cingg bug ...) > http://ffmpeg.org/pipermail/ffmpeg-devel/2019-September/250398.html > Input side hopefully already covered by ffmpeg.git patches (input image > format icc profile only should matter at decompressing into some pixel > array? Because further processing will alter those pixels ...or I am wrong > and input media profiles must be somewhat combined during track > compositing?) > > >
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