Image Trace: docs say Flat Logo averages down the decoded raster

An image over 64 megapixels is decoded at a smaller size first, and Flat
Logo averages that raster down in whole-number blocks.

docs/image-trace-adjustments.md

@@ -36,9 +36,9 @@ its own palettes are chosen; this is VectorCraft's own method (see
 slowly, and the trace says so: `imageTrace.make` returns the note in `warnings` and the status bar
 shows it (the [results optimization](https://helpx.adobe.com/illustrator/using/image-trace-results-optimization.html)
 page describes the same warning for images over 1500 px). An image of more than 64 megapixels (up to
-192) is traced from a copy scaled down to 64 megapixels, and the trace says that too. Flat Logo traces an
-image at most 1024 pixels on a side: a larger image is averaged down by a whole factor first (a 1025-pixel
-image is traced at 513), and the trace names both sizes in `warnings`. Flat Logo gives that note in place
+192) is traced from a copy scaled down to 64 megapixels, and the trace says that too. Flat Logo traces at
+most 1024 pixels on a side: a larger decoded raster is averaged down in whole-number blocks first (a 1025-pixel
+image is traced at 513, and a 16,000 × 12,000 image, decoded at 9,459 × 7,094, is traced at 946 × 710), and the trace names both sizes in `warnings`. Flat Logo gives that note in place
 of the slower-trace note for an image over 1500 pixels and in place of the 64-megapixel note. A trace that would
 make more than 8,000,000 anchor points (2,000,000 on the web) is refused to protect memory, with advice:
 raise Noise, lower Paths or Colors, or pick a lower-fidelity preset. A trace keeps

docs/target-app-parity.md

@@ -792,6 +792,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
 - **Image Trace, Auto Color rare colours:** the Automatic palette keeps colours too rare for its area count when they are distinct (Oklab) and drawn as coherent regions, at most six, protected from mixed-colour merging and Noise; code-drawn stem, highlight, low-contrast and scattered-noise tests (see [quality notes](image-trace-quality.md#auto-color-keeps-rare-colours)).
 - **Image Trace, source image on hold:** while the eye button next to the Image Trace panel's View is held down, the canvas shows the selected Image Trace objects' source image whatever their View, and shows their View again on release, with no change to the document or the undo history.
 - **Image Trace, large images:** images over 1500 px on a side trace with a warning in the result and the status bar; the anchor limit is 8,000,000 (2,000,000 on the web), measured at about 90 bytes an anchor (see [quality notes](image-trace-quality.md#large-images)).
+- **Image Trace, Flat Logo working size:** Flat Logo traces at most 1024 px on a side; a larger decoded raster (the 64-megapixel copy for a bigger image) is averaged down in whole-number blocks first, and the trace's `warnings` name the size it was traced at and the image's own size, in place of the slower-trace and 64-megapixel notes; code-drawn 1024 and 1025 px tests in `crates/trace` and `crates/engine`.
 - **Image Trace, Flat Logo working size:** Flat Logo traces at most 1024 px on a side; a larger image is averaged down by a whole factor first, and the trace's `warnings` name the size it was traced at and the image's own size, in place of the slower-trace and 64-megapixel notes; code-drawn 1024 and 1025 px tests in `crates/trace` and `crates/engine`.
 - **Image Trace, Preview:** the Image Trace panel's Preview checkbox, before Trace, is on by default, and a setting change traces the selected Image Trace object again at once. Off, changes wait in the panel until Trace applies them as one undo step, or until Preview is turned on again. Preview is kept with the UI preferences, and Reset to Default leaves it.
 - **Image Trace small contours:** closed fits too small to form an editable subpath retain their positioned outline, including holes. Source-generated island, hole/winding and stepped-region regressions cover Corners and Noise; defaults, parity scores and estimates are unchanged.