From about 50% zoom on the file of #4155, the pixels drawn are the full 141-megapixel photo,
and in a CMYK document they were separated into ink planes (or colorized, or proofed) whole
for every view: 8 to 9 s of white canvas a zoom step.
When the pixels drawn are larger than a 1,024-pixel tile, their colours are made again for the
frame and part of them is out of view, only the tiles in view are made, each kept under its own
key (`ImageKey::tile`), and drawn together as one pixmap so their edges don't show. The colours
are made pixel by pixel, so the result is the same as for the whole image. CMYK images painting
their own inks are still made whole.
Zooming in to 50%, 100% and 200% on that file went from 9.0, 8.6 and 8.7 s to 0.78, 0.05 and
0.05 s (M3 Pro, one run each), with the same pixels on screen.
With image mips on (the canvas, navigator and layer thumbnails), an image was colorized,
separated into the frame's ink plane and shown through Separations Preview's plates at its
full size, and only then shrunk to the mip drawn. The 141-megapixel image of #4155 made
1.6 GB of planes a frame, more than the image store holds, so every frame made them again.
The mip is now picked first and everything else is made from it, under the keys `kept_mip`
and `nearest_kept` already look up. A CMYK image's own inks are halved with its pixels
(`ink::key_inks`, `images::half_inks`), so it still paints them rather than inks separated
from its displayed colours. Colour bitmap glyphs follow the same order.
On that file the app's first frame went from 9.2 s to 1.6 s and the sharp frame after a pan
from 3.9 s to 8 ms (M3 Pro, one run each). Fine detail now shows its true average: 1-pixel
black and white lines show mid grey, where separating first showed them 44 levels darker.
Envelope Options stored Anti-Alias and Preserve Shape Using, but nothing that
draws an image read them: a distorted image was always smoothed and always
cut into clip groups.
- With Anti-Alias off, each piece of a distorted image is marked pixelated
(saved as `pixelated`). The renderer draws it with nearest-neighbor
sampling and without mips, SVG export writes `image-rendering: pixelated`,
and PDF export writes it without /Interpolate.
- With Preserve Shape Using Transparency, each piece is the image with a
white opacity mask in the piece's shape instead of a clip group. The
renderer paints an image whose mask is one plain white path straight into
that path, as it does for an image in a clip group, when the path lies
inside the image's frame.
Docs: docs/mcp.md, docs/target-app-parity.md.
Simon Hull