On Wed, 2008-07-23 at 04:10 +0100, Øyvind Kolås wrote:> On Mon, Jul 21, 2008 at 2:13 AM, Hubert Figuiere <hub@xxxxxxxxxxxx> wrote:> > Hi,> >> > I'm writing on RAW support for GEGL. I was wondering a few things:> >> > 1/ what is the best pixel format I should use for the CFA data. I chose> > "Y u16" because it is 16-bits (from 10 to 14 actually) and just the> > luminance. But it there something more suited?> > You could create additional new data types, that included the min/max> properties, that would still be 16bits wide but only use a limited> subset. Using u16 is probably a good route to take though.> Defining new additional formats would have to end up being a form of> fixed point perhaps calles something like f4.12 indicating a fixed> point format with with 12 bits allocated to values [0.0-1.0> OK so I was not off-chart. I'd rather stick to a standard u16 all thetime, and carry over the white and the black values (min and max). Thereare plenty of reasons, including that some provide a Gamma LUT. > > 2/ how do I propagate metadata? I need to specify the CFA pattern, the> > min and max values and other things need for the proper interpolation. I> > have no idea how to do that from the GeglOperation> > At the moment there is no way to propagate such auxiliary information> with the buffer, the existing demosaicing operations in GEGL take the> bayer layout as a parameter. We could add some special non grayscale> format that encoded which bayer pattern the grayscale data is stored> according to, this wouldn't allow babl to do the conversion but it> would allow specifying information about how the format is encoded.> > An approach that might be better than abusing babl by extending it> with additional models would be allowing to register additional> dynamic data in new dynamically allocated babl formats. Such a> capability will probably be needed when integrating with a color> management system that allows use of for instance ICC profiles, using> for instance littlecms for conversions. The problem for RAW data is that it is required. A CFA is meaningless ifyou don't have the pattern associated. Also I need to carry the min-max,eventually a LUT, the cam to xyz matrix / WB etc, eventually even acolor profile, etc (I probably miss some more, including rotation forFuji-CCD). Today, I need to open the file twice, once in GEGL, once outof GEGL for the metadata, to build the processing pipeline.[1] And I will not hide it: my ultimate goal is that GEGL be the defactoframework to deal with RAW files with libopenraw as the base, and theprocessing done in GEGL. Hub[1] or do it differently _______________________________________________Gegl-developer mailing listGegl-developer@xxxxxxxxxxxxxxxxxxxxxxxxxxx://lists.XCF.Berkeley.EDU/mailman/listinfo/gegl-developer
