Record dehaze's two passes in frame-budget.md

The figures are bee5c58's, quoted as that commit measured them: five passes to two, 22.9 ms to 9.1 ms at 2560 x 1600 fit and 54.1 ms to 28.1 ms at 4K, the output bit-identical. Under its own heading and status line, like the 2026-09-25 section, since this file was not re-run for them.
2026-09-26 14:55:18 -04:00
parent 0f7ea741d8
commit 2f5f2041ab
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@@ -474,3 +474,41 @@ sharpening at a scale too coarse to draw its radius emits an empty pass,
 which cost a full read and write when another neighbourhood operation
 followed it: sharpen with clarity at 2560 × 1600 fit went from 18.66 ms to
 14.16 ms, and at 3840 × 2160 from 37.93 ms to 27.88 ms.
 ## Dehaze in two passes — 2026-09-26
 **Status:** Measured in the commit named, not re-run for this file.
 **Dehaze erodes each axis in one pass and recovers in the second**
 (`bee5c58`, #74). It was five passes — a run and a span erosion along x,
 the same along y, and the recovery — and cost 22.9 ms of a 2560 × 1600
 frame on the laptop RTX 3050, 54.1 ms at 3840 × 2160, with the memory
 clock held at 810 MHz by the power cap. At those clocks a detail pass costs
 what it reads and writes rather than what it taps: a pass with an empty
 body, one render-sized `rgba16float` read and write, measured 4.0 ms, and
 each dehaze pass 4.4–4.6 ms, so the taps were about 2 ms of the 22 and the
 four hand-offs between passes were the rest. Each axis now takes the
 minimum over its whole window directly, and the recovery rides in the y
 pass, which already holds the veil and the pixel's own colour: 36 texture
 reads a pixel in place of 12, nearly all cache hits, and two passes in
 place of five.
 The same synthetic 60 MP source, only a detail parameter moving so the
 fused pass is reused, 30 frames a scene after six of warm-up, five runs of
 each binary alternated, median of the per-run p50:
 | scene | before | after |
 |---|---:|---:|
 | dehaze, 2560 × 1600 fit | 22.88 ms | 9.06 ms |
 | dehaze, 2560 × 1600 1:1 | 23.41 ms | 9.52 ms |
 | dehaze, 3840 × 2160 fit | 54.09 ms | 28.12 ms |
 | all five detail operations, 2560 × 1600 fit | 53.11 ms | 39.97 ms |
 | all five detail operations, 2560 × 1600 1:1 | 67.48 ms | 56.42 ms |
 | every operation with film, 2560 × 1600 fit | 57.59 ms | 44.19 ms |
 | every operation with film, 2560 × 1600 1:1 | 71.83 ms | 57.93 ms |
 The five detail operations are noise reduction, sharpening, clarity,
 texture and dehaze; the scenes without dehaze moved within ±2%. The
 picture is the same bits: a minimum is exact in any order, the window is
 the one the split passes covered, and the rgba8 output hashed identically
 before and after in all 64 scene, view and size combinations measured.