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3dtours e4f5407c19 web: each of the four tonal knobs moves its own band of the ramp and not the guard the four used to share
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.
2026-10-02 08:11:32 +07:00
3dtours bc550569ad web: BLACK keeps the picture's texture and not the base it was read off, clarity stops the blur at an edge instead of at a colour, and a backup folder that refuses is handed back to the picker
BLACK at full deflection returned a soft picture, and on a monochrome frame it
returned the blurred base outright. The tone pass reads the ramp at the
neighbourhood's base and then rebuilds the pixel, and it rebuilt it by the RATIO
the base had moved by — `Base' * (Input / Base)`, the other half of
fix_shadow.md's decomposition. A ratio is a gain, and that gain is a function of
the neighbourhood: the knob that takes the base toward zero scales every pixel's
detail by the same coefficient, so the knob that darkens the frame takes its
texture with it. Measured on lightroom_shadow.jpg at 1024px through tone-sim.mjs,
the pass in plain JS with the shader's own constants: at BLACK -100 the finest
gradient came back at 0.75 of the input under the ratio and at 0.98 under the
sum, while the frame darkened the same either way (mean 0.416 to 0.359 both). A
monochrome stock is the whole frame of that error, because all three channels ARE
the pixel's luma there, which is why the picture came back as the base — soft,
and short of every edge it had.

The reconstruction is `Base' + Detail`, ADDED and not scaled, and it costs
nothing where there is no move to make: with every knob on zero the ramp at the
base IS the base, so the difference is exactly zero and the pass is the identity
however coarse the base is. A caller that hands in no neighbourhood at all — a
mask — hands in the pixel's own image as its base and gets the global move back,
which is what the ratio gave it too. `o` is held inside the cube before the
detail is added, so a neighbourhood the ramp has pushed under the floor keeps the
structure around it instead of carrying its pedestal down onto every pixel in the
region. The bright side of the same move is untouched: the lift is still the
neighbourhood's, and at SHADOW +100 the band above the lifted knot still keeps
0.81 of its spread where the global move kept 0.42.

CLARITY drew a light stroke down every contour, and the reason was in what the
blur called a neighbour. The range weight was the colour difference,
`exp(-dot(d, d) * 24)`, which is loose on any coloured edge — two sides of a hair,
a branch or a rail can share a red and differ in green — so the reference reached
across the edge, and the reference is exactly what the blend subtracts. The wider
it reaches, the more a contour reads as detail. It reads LUMINANCE now, one
decision per tap at the doc's own scale (`CLARITY_RANGE_SIGMA` = 0.04), so an edge
of any hue stops the blur dead.

The blend moved the three channels by their own differences, which is what
coloured fringing along every contour was, and the amount it moved them by was
the MASK's `CLARITY_GAIN` borrowed for a different child. It moves LUMINANCE now
— one value carries the whole pixel back with it, so hue is untouchable and skin
does not go sallow at the top of the knob — under the doc's midtone weight
M(L) = 4L(1-L), which deepens the greys a picture is made of and leaves the burnt
ends and the deepest shadows where they are. The positive side's gain lives
inside the shader (4.5, raised from the doc's 1.8 because the range weight above
reaches less far and carries less detail): clarity-halo.mjs, which measures the
pass pushing a pixel outside the range of its own neighbourhood, reads a bright
stroke of 55.3/255 on lightroom_shadow.jpg and 54.3/255 on DSCF1701.JPG at +10,
against the old pass's 145 and 127 at the same knob — and 8.0 already reads 98, so
the knob does not need to go further to keep the flat areas moving.
`exportEngine` passes the knob's own units now, `[clarityKnob / 10]`, since the
gain and the sign are the shader's business and the mask's gain is not the
frame's.

And a backup folder the browser had stopped letting the page write to wrote
nothing and said so, once, with no way back: a permission outlives the tab only
while the tab does, so the row kept reading a permission of a moment ago while
the write went to the disk without one. A refusal that names the permission, or
the folder that is not there, now goes through the picker ONCE — the picker is
the only thing that hands a folder back — and the run is repeated; anything else
is the folder itself saying no, and is not asked twice. The sentence on the
screen is one line over a strip of photographs and cannot carry a reason, so the
reason goes to the console and a word of it into the note (`{why}`, the name the
browser gave the refusal and never a stack), which is the whole of what tells a
folder that was moved from a permission that lapsed. Both dictionaries learn the
word.

Checked: `tsc --noEmit` clean; `tone-base-check.mjs` and `highlight-knee-check.mjs`
updated to the new reconstruction and passing; `tone-sim.mjs` on
lightroom_shadow.jpg at 1024px for the numbers above; `clarity-halo.mjs` for the
stroke.
2026-10-02 07:20:31 +07:00
3dtours 166a677590 light: the tone ramp is four bumps on the identity, not straight segments between five knots — a knot is an angle, an angle in a tone curve is a Mach band, and the wedge reads the seams: BLACK +100 broke at 0.030 with 105 of second difference, HIGHLIGHT -100 at 0.747 with 72
The ramp was a0..a4 with the pixel's base interpolated straight between them.
A segment meets its neighbour at an ANGLE, and the second derivative of a tone
curve is what a gradient reads as a band — so a knob left a line across the
mid-tones, worst exactly where it was reported: BLACK +100 put its whole lift
inside 0.25 and the stretch from 0.25 up came back identical to the untouched
frame (the "transition stays grey" it was reported for), and HIGHLIGHT -100
folded a seam into 0.747, between the highlights it pulled and the shadow it
left under them.

Measured on a 1024-step luma wedge through the exported pass, second
difference through a ±1% box: BLACK +100 read 105 at 0.030 against 0.000 from
0.25 up, HIGHLIGHT -100 read 72 at 0.747. Step of the first derivative across
the knots: 0.955 at 0.25 and 1.146 at 0.75 — the curve arrived folded, and
1.146 is a sign flip, not a bend.

So each knob is now a BUMP on the identity, peaking on its own knot — BLACK on
0.00, SHADOW on 0.25, HIGHLIGHT on 0.75, WHITE on 1.00 — with the kernel
(1-u^2)^2 over a half-width (a half of the ramp for the two ends, whose knots
ARE the ends, a quarter for the two heads). Level at u = 0, so a knot moves
without a fold at its own top; level at u = 1, so a move lands on the identity
and on its neighbour without an angle; C1 everywhere between. The two bumps of
a half meet on 0.50 both on zero, which is the same fixed midpoint as before,
and DR still moves the same knots (0.12 on the toe, 0.18 on the head, half of
each on the heads beside them).

A sum of bumps can overshoot where two steep sides land on one stretch — past a
slope of 1 the curve runs BACKWARDS, a worse band than the seams this replaces,
and it is reachable: DR alone was under it, BLACK and SHADOW +100 together were
not (unguarded min slope -0.0141). The guard reads each pair at its own
steepest points, 8/(3*sqrt(3))/w per unit amplitude (TONE_BUMP_SLOPE_HALF 3.0792,
TONE_BUMP_SLOPE_QUARTER 6.1584), holds the two under one and gives them up
together past it. A single knob never reaches it (a full BLACK is 0.77, a full
SHADOW 0.77), so every slider keeps its whole travel; the worst case is DR at
full, which gives up a tenth of its head roll (0.18 -> 0.8376 on the head), and
BLACK with SHADOW both at +100, which arrive at 0.65 of their own lift instead
of folding. Guarded, the sweep over five levels of all four knobs and DR reads
a min slope of +0.0183 and a max of 1.9937, with the largest slope jump 0.00005.

After: the same wedge, the same pass. The knot steps are 0.096 at 0.25 and
0.478 at 0.75, with no sign flip — C1 across the knot instead of a fold. BLACK
+100 now carries the rework out of its own quarter: +0.139 at 0.25, +0.101 at
0.30, +0.033 at 0.40, 0.000 at 0.50, where it used to read 0.000 from 0.25 all
the way up. HIGHLIGHT -100 keeps its lift (-0.126 peak against -0.121 before) and
spends it over the quarter instead of into a line. Every knob on zero is the
identity to the last bit — the pass also runs for the stock split tones and for
DR alone — and 0.50 is still the one value no knob moves.

Checks: tone-base-check.mjs now runs the bump and the guard as arithmetic
beside the shader (with the negative control: the unguarded pair still folds,
the guard is what stops it). highlight-knee-check.mjs reads the kernel and the
two slope constants off the source, pins the four amplitudes and the guard, and
sweeps the travel of every knob as before. All ten checks that run without a
browser pass, build clean.

Skipped: the guard's ceiling is a constant, not a search for the widest travel
that still clears a band we cannot see. Add when a frame shows a band the
deflections in hand cannot explain.
2026-09-30 21:24:01 +07:00
3dtours 097e383b86 light: the tone base is a real blur, not nine point samples of one — the ring aliased the luma and the ramp painted the alias back as mottle
The base layer shipped last commit was nine POINT SAMPLES of the child, one
ring out at TONE_BASE_RADIUS. A ring is not an average, and on a frame with
texture at the ring's own scale it is worse than one: the nine lumas differ,
the sample pattern beats against the texture, and the base field comes out
aliased. The gain the pixel then rides, o(base)/base, is a function of the
base with a kink at every knot — so each alias of the base becomes an alias
of the gain, and the reconstruction paints it straight back over the detail
it was supposed to leave standing. Reported on a waterfall: grey patches
loose on a mountainside, a smear across the face of the falls, and plateaus
in cloud and sky (the pass runs whole-frame, so its base is read in the
bright end too).

Measured, 1160x774 at SHADOW +100, the high-frequency part of the gain field
(9px high-pass, where a real base can hold none): 0.0627 for the ring,
0.0048 for a blur of the same radius. Thirteen times. The fix is not more
taps — a 7x7 at a third of the step is still point samples, only smaller —
it is to stop sampling: the caller blurs.

So the base is now a second CHILD of the tone pass, the frame blurred by
Skia's own MakeBlur (blurredBase in exportEngine.ts, the draw drawBlurred
already made for the sharpening pass) at TONE_BASE_RADIUS of the frame width
and sigma TONE_BASE_SIGMA of that radius — a box's equivalent at the radius,
so the neighbourhood is the one the radius always named and the cuts are
smooth instead of hard. The shader reads it ONCE per pixel and baseLuma
loses its loop and its `bx`. That is also the cheaper pass: nine child evals
walked the exposure/matrix chain nine times, one eval does not.

A caller with no frame to blur hands in the image it is already shading as
the base. The tap then lands exactly on t and the ramp is the global move
again — a mask's degenerate bx of zero, spelled as a child that IS the
source, which is what gradientMask.ts's own call (base == t) already meant.

Checks: tone-base-check.mjs is new — SkSL is only compiled at runtime and
nothing here compiled TONE_SKSL whole, so the pass is compiled and rendered
for real, with the frame and the base held at two flat values a little
apart: the pixel has to land on the value the ramp over THAT base predicts
(171 for a 128 pixel over a 76 base), and a base equal to the pixel has to
be the identity. highlight-knee-check now pins the one tap, the absence of
`bx`, the blur, and the two-child wiring. 9/9 pass, build clean.

Skipped: no guided filter proper — the base is a plain blur, so a strong
edge is no longer held out of it the way the range weight held it (a dark
rock a blur's width from the water reads a lifted base and keeps its own
darkness). Add when a frame shows the halo; the doc asks for a plain blur
and this is one.
2026-09-30 19:03:55 +07:00