Previews looked more saturated than the exported files on Mac screens. The
pixels are the same: preview and export match to within one level on the CPU
and GPU paths, and exports embed a correct sRGB profile. But wgpu leaves the
window's Metal layer without a colour space for sRGB surfaces, and Core
Animation shows such a layer without colour matching ("If nil, no
colormatching occurs", CAMetalLayer.h). On a P3 screen the sRGB previews
were therefore shown too saturated, while Preview and Photos convert the
exports properly.
While no monitor profile is chosen in Settings > Display, the desktop app now
shows previews through the profile of the screen the window is on
(NSWindow.screen.colorSpace.ICCProfileData, safe objc2 calls), through the
existing display-profile path. It is read again about once a second, so
moving the window to another screen is followed. A chosen profile still wins;
"Use Screen Profile" goes back to it. app.displayProfile reports it as
path: null, screen: true. Other platforms and headless sessions are
unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Previews were always sRGB, which wide-gamut monitors show oversaturated.
Settings > Display > Choose Profile... (and the UI command
app.displayProfile) now shows photos through the monitor's ICC profile,
matrix/TRC or LUT-based.
- codecs: DisplayProfile (moxcms): the display's primaries (colorant tags,
or measured through the A2B tables of a LUT-only profile), the proxy ->
device correction (per-channel curve tables for matrix/TRC profiles, a
CMS transform for LUT profiles) and sRGB <-> display transforms.
- pipeline: DisplaySpace / RenderRequest::display: the per-pixel stage
renders into the display's primaries and gamut maps into its gamut
(CPU and GPU: only to_out / out_luma change). Soft proofing's display
gamut warning uses the display's gamut.
- engine: RenderJob::with_display; display::present converts sRGB
results (thumbnails, cached previews, embedded JPEGs). Histograms and
the preview caches stay sRGB; exports are unchanged.
- ui: the loupe, Before, Compare, hover and second window render for the
display; everything else is converted on the render workers. Settings >
Display tab, ui.json setting, file picker opening in the system's ICC
folder.
Tests: profile parsing and transforms (sRGB, P3, gamma 2.2, a synthetic
LUT-only profile, corrupted files), display renders equal 8-bit renders
into the matching output space, sampled histograms, and a headless UI test
of the whole flow. docs/display-profiles.md describes the design.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WEuxxPyG8t6KcADbZSEAUj
lloyd
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