lightcraft/docs/hardware-parity.md

Hardware parity

Last reviewed: 2026-10-10 · Last updated: 2026-10-12 · Change: minor (pen pressure for brush masks); previously major (created from the code, gpu-pipeline.md and the parity checklist) · Target: Adobe Lightroom Classic 15.5 / Lightroom 9.6

What Lightroom does with the machine's hardware, per platform, and what LightCraft does. Sources: gpu-pipeline.md, display-profiles.md, denoise.md, ai-masks.md, crates/gpu, crates/engine/src/devices.rs, crates/ui-egui/src/panels/second.rs.

Feature	Target	LightCraft: macOS	Windows	Linux / BSD	Web	Status
GPU for display and editing	Metal / DX12, "Use GPU for display / image processing / export"	wgpu Metal: geometry, resize, blur, WB, NR, guided filter, dehaze, masks, finish; CPU fallback per render	DX12 only (Vulkan opt-in, #136)	Vulkan	CPU only (no WebGPU yet)	🟡 defringe, spot removal, heuristic masks, long brushes and high-bit exports stay on CPU
GPU export	✅	✅ (6000 × 4000 in ~0.3 s vs ~1.2 s CPU)	✅	✅	—	✅ (black-export fix on an Intel iGPU, #78)
AI on GPU / neural engine	Metal / DirectML / Core ML, model per feature	AI denoise on GPU or CPU (setting); SAM 3 on Metal via candle; faces on CPU	CPU / GPU denoise	CPU / GPU denoise	—	🟡 no Core ML / Neural Engine / DirectML
HDR (EDR) display	✅ (macOS EDR, Windows HDR)	⬜	⬜	⬜	⬜	⬜ (LR-VIEW-HDR-DISPLAY)
Monitor profile	automatic per display, follows the window	🟡 picked by hand	🟡	🟡	—	🟡 OS profile not read; no follow across monitors
Second window / second monitor	✅ (Classic)	✅ (⌘F11)	✅	✅	—	✅ (Classic secondary-window keys missing)
Pen pressure / tilt (brush masks)	✅ pressure for size / flow	⬜ winit reports no tablet pressure on macOS	🟡 pen force from winit touch events (untested on a tablet)	⬜ winit has no X11 / Wayland tablet input	🟡 pointer-event force where winit passes it	🟡 brush size and flow follow pen pressure wherever egui gets a touch force (Brush ▸ Pen Pressure); no tilt; macOS / Linux tablets wait on winit
Trackpad gestures	pinch zoom, pan	✅ pinch, two-finger pan	🟡 (winit)	🟡	🟡	✅ on macOS
Card readers / cameras as import sources	✅ (devices panel, eject after import)	✅ mounted volumes with DCIM	✅	✅	—	🟡 no eject-after-import check, no MTP / PTP phones
Tethered capture	✅ Classic (Canon, Nikon, Sony, Leica)	⬜	⬜	⬜	—	⬜
Printers	✅ Print module, printer colour management	⬜ (PDF contact sheets only)	⬜	⬜	—	⬜
Control surfaces (MIDI / Loupedeck via plug-ins)	via SDK plug-ins	control channel and MCP can drive every command	same	same	—	🟡 different mechanism; no MIDI mapping
Multi-core CPU	✅	✅ worker pools, parallel JPEG decode, parallel import copy	✅	✅	single thread	✅
Memory pressure	managed	✅ memory budget, crates/sysmem returns allocator pages on macOS	✅ budget	✅ budget	—	✅

Score

~40% ready (estimated): the GPU editing path is real and fast (measured: 24 MP exposure drag 3.9 ms on GPU vs 22–42 ms CPU; NR drag 18 ms vs 301–471 ms), but HDR display, pen pressure, tethering, printing, automatic monitor profiles and neural-engine inference are missing. GPU correctness is proven on Apple GPUs; other vendors rely on user reports.

Remaining (Opus 5.5 agent hours)

Work	Hours	Needs
HDR display (EDR on macOS, Windows HDR, Linux where possible)	10–20	an HDR display to verify (human)
OS monitor profile, follow window across displays	5–10	multi-monitor setup
Pen pressure for brush masks: done where winit reports a touch force; macOS and Linux tablets need winit tablet events (or a pure-Rust tablet layer)	3–8	a tablet
Remaining stages on GPU (defringe, spot removal, masks)	10–20
Tethered capture (PTP over USB in pure Rust, Canon / Nikon / Sony first)	25–45	cameras (human)
Printing with colour management	15–25	printers (human)
Neural-engine / DirectML inference for AI features	10–20	depends on the AI model decision
Total	80–150 h (the core set for beta, HDR display + monitor profile + pen pressure: 20–40 h)

Revision history

Date	Change	Summary
2026-10-12	minor	Pen pressure: strokes record per-point pressure from egui touch force, scaling dab size and flow; per-platform status
2026-10-10	major	Created