A stop is a multiplier on light, so EXPOSURE and EV stop living in the sRGB
colour matrix and get a linear-light pass of their own (EXPOSURE_SKSL:
linearise, `C * 2^EV`, re-encode). The matrix keeps CONTRAST: a gain on encoded
values is what made +1 EV land at x1.5 instead of x2. Measured on the neutral
PROVIA sim: EV +1 = x2.011, EV +2 = x3.999, still unclipped at 239.
The pass sits between the matrix and the tone shader, and the tone / cinema /
curve / glow / halation children all sample through it, so HIGHLIGHT finally
sees the value exposure produced instead of the one before it. Recovery keeps
`L + strength * mask * (1 - L)` over `smoothstep(0.50,1.00,luma)`, and the
colour comes back as `color * (luma_new / luma)`: a blown white stays white
(255 -> 255 at -10, 255 at +10), a 0.8 grey loses 33 luma, the midtones beside
it do not move.
AUTO is the histogram the LIGHT tab already draws: weighted mean luminance
(guard 0.001), target 0.48, `log2(0.48 / avg)` clamped to +-2.5 EV, handed to
the same knob. A 0.251 grey asks for EV 0.9 and lands at mean 83.0 against the
83.3 predicted, idempotent on a second press. A stock's own bias rides the same
pass (`SIM_EXPOSURE_BIAS_EV`, VIVID +0.25 EV) and cancels against the knob, so
-1 EXPOSURE on VIVID returns the CLASSIC rendering (measured 0.4149 vs 0.4177).
ponytail: the phone app's `src/utils/colorUtils.ts` keeps the old math, so the
two copies have to move together; recipes saved before this commit (EXPOSURE 2,
HIGHLIGHT +-1) render under the new stop semantics.
Verified on the rebuilt container (BASE=http://localhost:8090):
- web-exposure-probe.cjs 20 PASS / 0 FAIL (neutral 128 -> 128, EV +1 ratio
2.011, EV +2 ratio 3.999, EXPOSURE +10 ratio 5.62 / -10 ratio 0.172, AUTO
EV 0.9, HIGHLIGHT -10 on a 204 grey 204 -> 171, white 255 -> 255, no console
errors)
- sim-exposure-test.cjs 9 PASS / 0 FAIL (classic 0.4149, vivid 0.4531, knob -1
returning 0.4177, bias 0.0382)
- regression suite, 28 probes: mask 53/0, brush-edit 35/0, heal-idle 23/0,
heal-zoom-drag 28/0, sims 31/0, sim-vivid 9/0, white-black 4/0, temp-swatch
33/0, tone-curve clean, compare 25/0, create 52/0, wb-preset 33/0, zoom 25/0,
save-recent 25/0, web-smoke 9/0 (its export step was stale — EXPORT opens a
size picker now). panel-test 4 FAIL, histogram-wb 1 FAIL, studio-save-hl and
progate timeouts, landing-test 6 FAIL ($0.99 pricing) are pre-existing.
- npx tsc --noEmit clean.
3dtours
7e47a153b8