For example, let's say I'm developing a gimp plugin and I'm using
gegl_buffer_iterator_* to get the data. And I want to manipulate the data in
profile connection space CIE xyY. I have:
```
...
GeglBuffer *buffer;
const Babl *format;
GeglBufferIterator *iter;
buffer = gimp_drawable_get_buffer(drawable_ID);
format = babl_format("CIE xyY float");
iter = gegl_buffer_iterator_new(buffer,
..., ...,
format,
..., ..., ...);
while (gegl_buffer_iterator_next(iter))
{
...
```.
And this seems to work fine if the color profile in gimp is set to sRGB. for
example, with pure sRGB green (#00ff00), the gegl_buffer will get me xyY 0.32,
0.58, 0.72, which seems about right.
The problem becomes when I convert the image in gimp to something like
ProPhoto. Gimp correctly converts the pure green to be represented with
something like ProPhotoRGB #8aed4e, which is probably still around the same
green as before in profile connection space. So far, so good.
But then, when I try to read this drawable with gegl_buffer:
```
...
GeglBuffer *buffer;
const Babl *format;
const Babl *profile = babl_space("ProPhoto");
GeglBufferIterator *iter;
buffer = gimp_drawable_get_buffer(drawable_ID);
format = babl_format_with_space("CIE xyY float", profile);
iter = gegl_buffer_iterator_new(buffer,
..., ...,
format,
..., ..., ...);
while (gegl_buffer_iterator_next(iter))
{
...
```,
I get xyY 0.36 0.51 0.67, which differs from before. xyY should be agnostic to
the color space as it is a profile connection space. It's almost as if the
gegl_buffer interpreted the #8aed4e color as sRGB and not as ProPhotoRGB, which
then kinda matches the result.
Is there a way for gegl_buffer to interpret the drawable data using the correct
color space? Is there a libgimp way to get the assigned image profile to use it
with gegl? Or is it better to load the buffer with something like
babl_format("RGB float") and then use babl_fish() to manually convert to xyY?
Thanks
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