BLACK, SHADOW, HIGHLIGHT and WHITE were four bumps summed into the identity,
and the sum carried a guard: the two bumps of a half shared a slope, so past a
total of 1 the curve folded backwards, and the ceiling that stopped it was
shared by the amplitudes of a half. A stock already sitting on SHADOW therefore
took BLACK's lift down with it — on the monochrome stock (sh = -0.24) BLACK at
-100 came back with 0.663 of the travel the knob has on its own, which is the
"kéo theo sự thay đổi của thông số khác" report exactly.
thay_doi_thong_so_giong_lightroom.md section 2 asks for four WINDOWS instead:
each knob owns a compact band of the ramp and is exactly zero outside it, and
the four moves are applied ONE AFTER ANOTHER rather than summed. A composition
of monotone maps is monotone by construction, so it needs no guard, and each
knob then measures 1.00 of its travel on every stock. BLACKS is the doc's toe —
u = clamp(1 - L/0.18, 0, 1) cubed, opened by sqrt(L) - L at 0.7 and deepened by
0.85, both of which are exactly zero at L = 0, so (0,0,0) stays (0,0,0): the
grey pedestal that BLACK +100 left on a black was the sum adding its bump's
height at the black point, which is the doc's own "Milky / Foggy". SHADOWS is
the doc's bell over the deep tones, HIGHLIGHTS the bell over the bright ones,
WHITES the doc's Hermite on the shoulder from 0.80. The ramp keeps its two
anchors — 0.00 and 1.00 — at every setting of the four knobs.
One deliberate departure from the doc: HIGHLIGHT carries a (1 - L) the doc's raw
knee does not, because pow(L - 0.5, 1.5) added to L overshoots the cube above
0.94 — 17% of the ramp driven to flat white at +100 before the clamp. Read
against the headroom that is left, the move is zero at L = 1 by construction and
the head rolls instead of clipping.
The windows are read in the sRGB-encoded luma this file already works in, not in
linear light as the doc's section 1 sets out: the doc's own boundaries (0.18,
0.05..0.45, 0.55..0.95, 0.80) land as perceptual positions there, and moving the
whole renderer to the linear domain is a bigger change than this pass. The
divergence is the one the scratchpad compat doc already warns the Android port
about, and it is noted at the windows themselves.
Checked: `tsc --noEmit` clean; `highlight-knee-check.mjs`, `tone-base-check.mjs`
and `mask-wb-check.mjs` updated to the four windows and passing; the twin ramp
over a 1/512 grid is monotone to -0.00119 (0.30 code values, at t = 0.098 with
every knob at full negative), both anchors hold for every combination, and a
knob outside its band is the exact identity.
3dtours
e4f5407c19