Brightness, contrast, saturation, and gamma adjustments before palette
quantization. Pure-function applyColorCorrection in src/lib keeps the CLI
and browser importer in sync. Inserted post-resize so slider moves stay
responsive on large sources; precision loss is negligible through a
32-color palette.
UI is a collapsible "Color correction" section with four sliders, live
values, a "Reset" button, and an "on" badge when any value differs from
default. CLI gains --brightness, --contrast, --saturation, --gamma
(all -100..+100 except gamma which is 0.1..3.0).
9 unit tests pin down identity, saturate-to-0-or-255 clamping, greyscale
at saturation=-100, gamma midtone direction, and alpha preservation.
Replace the single Floyd-Steinberg toggle with a method dropdown offering
none, floyd, atkinson, jarvis, burkes, sierra, sierra-lite (error diffusion)
and bayer-2 / bayer-4 / bayer-8 (ordered). Kernels live in
src/lib/dither-kernels.js as plain data; rgbaToPalette dispatches via a
shared runErrorDiffusion runner and a runOrderedDither for Bayer.
The legacy `dither: true` option keeps working (maps to `method: 'floyd'`),
so existing CLI invocations and tests stay green. CLI gains
`--dither-method <name>` which takes precedence over `--dither`.
13 unit tests cover exact-palette hits, transparent pixels, all-method
smoke, kernel weight sums (Atkinson=0.75, others=1.0), and verify Bayer
actually scatters on mid-grey where plain nearest would produce one color.
Pure-function transformRgba in src/lib/image-transform.js supports flip H,
flip V, and rotation in 90° steps (fixed application order: rotate → flipH
→ flipV). Wired into the importer pipeline before resize with buttons for
each op; ±90° rotations auto-swap the resize dims so output aspect tracks
the rotation. CLI gains --flip-h, --flip-v, --rotate flags using the same
shared module.
8 new unit tests cover identity, each flip, 90/180/270 rotation, the
flipH+flipV ≡ 180° identity, and invalid rotation rejection.
CanvasRenderer.setOverlay draws the palette-converted import preview on top
of committed + pending layers at (x, y) with a configurable alpha. Image
importer gains an "Overlay" toggle and opacity slider; the overlay
reactively follows resize/dither/origin changes and clears on panel close,
toggle-off, or image swap. Lets the user align the upload before spending
credits.
Six phases spanning resize, on-canvas overlay preview, transforms, more
dithering algorithms, color correction, and skip-white/paint-transparent
toggles. Based on WPlace-AutoBOT's image-processor.js feature set, scoped
to what fits our 32-color canvas.
Three review reports (backend, frontend, security/scale) and a
follow-up re-review after pull. Plan documents which findings were
addressed in this sweep and which were intentionally deferred.
tiennm99