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LibPDF+Meta: Use a CMYK ICC profile to convert CMYK to RGB

CMYK data describes which inks a printer should use to print a color.
If a screen should display a color that's supposed to look similar
to what the printer produces, it results in a color very different
to what Color::from_cmyk() produces. (It's also printer-dependent.)

There are many ICC profiles describing printing processes. It doesn't
matter too much which one we use -- most of them look somewhat
similar, and they all look dramatically better than Color::from_cmyk().

This patch adds a function to download a zip file that Adobe offers
on their web site. They even have a page for redistribution:
https://www.adobe.com/support/downloads/iccprofiles/icc_eula_win_dist.html

(That one leads to a broken download though, so this downloads the
end-user version.)

In case we have to move off this download at some point, there are also
a whole bunch of profiles at https://www.color.org/registry/index.xalter
that "may be used, embedded, exchanged, and shared without restriction".

The adobe zip contains a whole bunch of other useful and fun profiles,
so I went with it.

For now, this only unzips the USWebCoatedSWOP.icc file though, and
installs it in ${CMAKE_BINARY_DIR}/Root/res/icc/Adobe/CMYK/. In
Serenity builds, this will make it to /res/icc/Adobe/CMYK in the
disk image. And in lagom build, after #23016 this is the
lagom res staging directory that tools can install via
Core::ResourceImplementation. `pdf` and `MacPDF` already do that,
`TestPDF` now does it too.

The final piece is that LibPDF then loads the profile from there
and uses it for DeviceCMYK color conversions.

(Doing file access from the bowels of a library is a bit weird,
especially in a system that has sandboxing built in. But LibGfx does
that in FontDatabase too already, and LibPDF uses that, so it's not a
new problem.)
This commit is contained in:
Nico Weber 2024-01-30 21:04:37 -05:00 committed by Andrew Kaster
parent f840fb6b4e
commit 9c762b9650
6 changed files with 65 additions and 7 deletions

View file

@ -6,7 +6,10 @@
#include <AK/ByteString.h>
#include <AK/Forward.h>
#include <AK/LexicalPath.h>
#include <LibCore/MappedFile.h>
#include <LibCore/ResourceImplementationFile.h>
#include <LibCore/System.h>
#include <LibGfx/Bitmap.h>
#include <LibPDF/CommonNames.h>
#include <LibPDF/Document.h>
@ -293,6 +296,12 @@ TEST_CASE(postscript)
TEST_CASE(render)
{
#if !defined(AK_OS_SERENITY)
// Get from Build/lagom/bin/TestPDF to Build/lagom/Root/res.
auto source_root = LexicalPath(MUST(Core::System::current_executable_path())).parent().parent().string();
Core::ResourceImplementation::install(make<Core::ResourceImplementationFile>(MUST(String::formatted("{}/Root/res", source_root))));
#endif
auto file = MUST(Core::MappedFile::map("colorspaces.pdf"sv));
auto document = MUST(PDF::Document::create(file->bytes()));
MUST(document->initialize());