TINT, the same two rulers, read on the mask's own pixels.
The pair was asked for as the two rows the develop column already has, so it is
the same pair and not a second opinion about what a kelvin means: the gain comes
from one function, colorUtils.whiteBalanceGain(temperature, tint), which the
frame-wide colour matrix now calls too — the RGB kelvin fit of kelvinToRGB, the
symmetric ±0.08 magenta/green tint, and the division by the product's own Rec.709
luma that keeps a cast from being a brightness move. A mask that never touched
the pair reads 5500K / 0 (readMasks' own defaults, clamped to the ruler's ends),
whose gain is exactly (1,1,1), so nothing moves and every recipe stored before
this reads the same. The measured rule holds inside a mask exactly as it does on
the whole frame: at 10000K the mask's pixels came out R/B 1.25 -> 1.72 against
0.994 -> 0.994 outside it.
The Kelvin fit is a curve, so it is resolved on the JS side and handed over as a
gain: maskUniforms grows one more float4 array (wb[i], three gains and a zero
pad) between the spatial pair and the frame size, in declaration order like every
other array in that buffer, and the shader multiplies the mask's colour by it
right after EXPOSURE — one clamp, three multiplies by one for a mask that leaves
the pair alone, and no second copy of the fit in SkSL. The spatial build is a
second shader text with a second signature and reads the same array.
App.tsx draws the rows where the panel's other rows already are, and TINT rides
the existing maskKnobRow helper: same store unit (±10), same ±100 slider the
frame-wide row wears since the develop knobs were deepened. COLOR TEMP keeps its
own scale (2500..10000, step 100, "10000K"), because a temperature is not a
percentage, and it carries the same swatch the frame-wide row paints.
Verified: npx tsc --noEmit; npm run build; the repo's check set (highlight-knee,
auto-tone, half, white-level, preview-match, library, scan-nav, roll-walk) all
pass; and scripts/mask-wb-check.mjs, which is new here — it transpiles the
gradientMask graph into a temp dir and checks the gain (neutral at 5500K/0, warm
at 10000K, cool at 2500K, luma-preserving, ±TINT symmetric), the clamps, the
uniform offsets (the gain lands where the shader reads wb[i], the frame size one
array further on), and then compiles the real shader through CanvasKit and pushes
a mid-grey through it: neutral leaves 128, 10000K warms it, +TINT magenta-ises it,
and both the plain and the spatial builds and a two-mask list read it. The UI was
driven on the built bundle too (a linear mask dragged on the preview, then the
two rulers moved through their own range inputs): the mask column reports 11 rows,
opens at 5500K / 0, takes 10000K and +40 ±100-scale TINT, the swatch follows, and
the preview's own pixels warm inside the mask and nowhere else.
ponytail: the mask's WB is not skipped for monochrome stocks the way the
frame-wide matrix skips it — a local kelvin on a B&W frame is a tint someone
asked for by hand, not the colour leak that rule exists to stop. Add the same
isMonochromeBase guard (and pass the base filter into maskUniforms) only if that
turn out to read wrong on a live B&W recipe.
Co-authored-by: PenguinHarness <noreply@penguin.local>
3dtours
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