Hi Tomi, On Monday, 18 December 2017 14:04:45 EET Tomi Valkeinen wrote: > On 18/12/17 13:50, Laurent Pinchart wrote: > > That's an option too. I had a look at the code once to find out how > > ImageMagick was performing scaling and gave up with a headache soon > > afterwards. We need more formats than what ImageMagick currently supports > > (it's mostly focused on image file formats instead of raw image formats), > > with all kind of RGB, YUV (and ideally Bayer) formats, and I don't think > > extending ImageMagick would be the way to go. > > Yep, I can image that ImageMagick can't handle it all. I don't really > have much experience with it. I did find that it has enough tunables to > manage rgbx8888 with different byte orders and the "extra" alpha channel: > > convert -depth 8 -size $1x$2 -color-matrix "0 0 1 0 1 0 1 0 0" -alpha > deactivate rgba:$3 png:- > > But things like argb1555 or yuv422 might prove to be too difficult for > ImageMagick. > > Where's the source for v4l2convert? What does it do? Sorry, it's v4lconvert, not v4l2convert. The library is part of v4l-utils (available at git://linuxtv.org/pinchartl/v4l-utils.git) and is found in the lib/libv4lconvert directory. The purpose of the library is to convert from lots of weird formats supported by V4L2 to RGB or YUV. It was initially written to handle vendor-specific compression formats used by webcams, has been extended to support Bayer formats and different kind of RGB and YUV formats. The code is simple, I think it could be a good base. > I wonder how difficult it would be to create a brute-force-no-optimizations > style of a function to which you give the exact bit definition of the > buffer's pixel format, and which gives you RGB888 or YUV444, depending on > the input format (I presume most image encoders would accept RGB888 & > YUV444). Can you come up with a bit definition format that could describe Bayer or tiled formats without requiring the definition to be written in an interpreted language ? :-) > I think the function wouldn't even need to care whether the data is RGB > or YUV, it would just unpack it according to the format definition. -- Regards, Laurent Pinchart
