December 20, 2025
Byte-sized brawl
Maximizing Compression of Apple II Hi-Res Images
Retro crowd splits: tiny byte savings, big Woz blame vs “use smarter tricks”
TLDR: A retro dev shrinks Apple II hi‑res images a bit using a standard compressor and a de‑interlacing trick. Commenters argue the gains are too small to justify extra code and time, with “don’t blame Woz” pushback and calls for smarter predictive methods — a trade‑off worth knowing for vintage projects.
Apple II diehards are feuding over a retro dev’s attempt to squeeze hi‑res images smaller. The project uses a standard 6502 compressor (zx02) plus a “de‑interlace” trick to reorder pixels, shaving off modest amounts — think 951 → 808 bytes on a game scene, 2572 → 2402 for a Christmas card, 3423 → 3263 for a Riven shot, and 5176 → 5094 for an icy warrior auto‑convert via iipix. Sounds neat, but there’s time overhead too: roughly 417ms to decompress, plus ~118ms and ~232ms for add‑backs and de‑interlacing. Cue the comments lighting up like a CRT.
The strongest opinion: ajross calls it “somewhat disappointing,” saying it’s just off‑the‑shelf compression with a pixel shuffle and grumbling at the casual “blame Woz” reasoning for Apple II’s weird screen layout. Meanwhile, kazinator drags out the calculator: if you save a few hundred bytes on disk but spend more than that in extra code in memory, it’s a no‑win in RAM — and that “four images before net win” line applies to floppy space, not what you’ve got loaded. Then Dwedit storms in with the hot take: real max compression means predictors (looking at the pixel above and left) instead of raw data. The peanut gallery piles on with jokes: “Woz saved chips, not your bytes,” and “Floppy vs RAM: choose your fighter.” It’s classic retro drama — tiny savings, big feelings, and a call to bring smarter math to the party.
Key Points
- •Update dated 20 December 2025 on compressing Apple II Hi-Res images.
- •zx02 compression is the baseline; a de-interlace preprocessing step further reduces size.
- •Across four 8 KB images, de-interlace improves compression by 82–170 bytes and ~2 percentage points.
- •Measured overhead: zx02 decompression 426,538 cycles (~417 ms, ~25 frames); add-back-holes 121,031 cycles (~118 ms, ~7 frames); de-interlace 237,414 cycles (~232 ms, ~14 frames).
- •Results are shown for Kerrek 1, Christmas, Riven Maglev, and Ice Warrior images with specific compressed sizes and percentages.