I didn't put this as a method on Bitmap since it doesn't seem generally
useful. Easy to move the impl over to Bitmap in the future if we want
to use it elsewhere.
This is useful for timing just decoder performance.
(It'd be nice to add a `-t` flag that prints timings for all
the different phases, but for now just disabling writing is
sufficient for me.)
As we directly write to the stream, we don't need to store a copy of the
entire image in memory. However, writing to a stream is heavier on the
CPU than to a ByteBuffer. This commit unfortunately makes `add_pixels`
two times slower.
For now, only for color spaces that are supported by Profile::to_pcs()
and Profile::from_pcs(), which currently means that all matrix profiles
(but not LUT profiles) in the source color space work, and that
matrix profiles with parametric curves in the destination color
space work.
This adds Profile::convert_image(Bitmap, source_profile), and
adds a `--convert-to-color-profile file.icc` flag to `image`.
It only takes a file path, so to use it with the built-in
sRGB profile, you have to write it to a file first:
% Build/lagom/icc -n sRGB --reencode-to serenity-sRGB.icc
`image` by default writes the source image's color profile
to the output image, and most image viewers display images
looking at the profile.
For example, take `Seven_Coloured_Pencils_(rg-switch_sRGB).jpg`
from https://commons.wikimedia.org/wiki/User:Colin/BrowserTest.
It looks normal in image viewers because they apply the unusual
profile embedded in the profile. But if you run
% Build/lagom/image -o huh.png --strip-color-profile \
'Seven_Coloured_Pencils_(rg-switch_sRGB).jpeg'
and then look at huh.png, you can see how the image's colors
look like when interpreted as sRGB (which is the color space
PNG data is in if the PNG doesn't store an embedded profile).
If you now run
% Build/lagom/image -o wow.png \
--convert-to-color-profile serenity-sRGB.icc --strip-color-profile \
'Seven_Coloured_Pencils_(rg-switch_sRGB).jpeg'
this will convert that image to sRGB, but then not write
the profile to the output image (verify with `Build/lagom/icc wow.png`).
It will look correct in image viewers, since they display PNGs without
an embedded color profile as sRGB.
(This works because 'Seven_Coloured_Pencils_(rg-switch_sRGB).jpeg'
contains a matrix profile, and Serenity's built-in sRGB profile
uses a matrix profile with a parametric curve.)
If the input file didn't exist at all, the TRY(MappedFile::map())
gives us a (cryptic) error message, but if it existed but wasn't an
image file, we would crash. Now we print a message instead.
This allows assigning a color profile from a .icc file to the output.
No pixel data conversion is taking place: the output will just contain
this profile, so it better matches the image data already.
This probably does strange things for CMYK jpegs, since JPEGLoader
converts those from CMYK to RGB but the ICC profile is still an CMYK
profile. The Right Fix for that is probably for JPEGLoader to consume
the profile when it does CMYK->RGB conversion and then not hand out
the profile data. (Or we could add a CMYK bitmap type.)
But most of the time, this is a progression :^)
At the moment, all it can do is read all image formats that LibGfx can
read and save to any image format that LibGfx can write (currently bmp,
png, qoi).
Currently, it drops all image metadata (including color profiles).
Over time, this could learn tricks like keeping color profiles,
converting an image to a different color profile, cropping out a part of
an image, and so on.
