i IMI FORMAT Auto-Optimizing Encoder Lab

Auto-Optimizing Candidate Tournament · Live WASI Evaluation

See What the Encoder Tries — and Why the Winner Wins

Instead of guessing flags, pick any dataset below (or upload your own PNG). The auto-optimizer runs candidate encoding strategies in sequence—showing every candidate it tried, its exact byte size, decode speed, and internal syntax trace, why suboptimal candidates lost, and why the ★ Winning Strategy was chosen.

1. Pick a Dataset (or Upload a PNG) to Run the Auto-Optimizer Tournament

★ Auto-Optimizer Verdict

Click a dataset above or press Run Auto-Optimize Tournament to evaluate candidate encode strategies live in WebAssembly.

Step & Candidate Strategy Tried CLI Flags Encoded Bytes bpp (% of Raw) Quality (HaarPSI / SSIM / PSNR) Decode Speed Syntax Tools Chosen & Verdict

Automated Encoder Settings & Codestream Telemetry (★ Winning Stream)

2. Why Each Feature Exists in the IMI Format

SPEC §2.1 Map 9 · Value-Table Channel Maps

Sparse 16-Bit Scientific Sensors

16-bit detector and astronomy arrays often populate only a few hundred distinct codes out of 65,536. Without compaction, spatial predictors see large numeric jumps between adjacent codes. Map 9 compacts active codes into dense indices 0..K−1 before prediction, shrinking sparse 16-bit files by 3.9×.

SPEC §2.6 · Template Palettes & Bilevel Contexts

Dithered Graphics, UI & Masks

Linear predictors (clamped gradient) fail when pixels alternate between discrete palette entries or 2-level masks. Effort 10 trials spatial template palettes and 2-value neighborhood contexts alongside predictors, picking the palette/bilevel coding only when it beats spatial prediction (2.9× smaller on dithered art).

SPEC §2.13.1 · Quick Bit-Smart Byte Planes

Why Bit-Smarts Exist in Quick Mode

Lossless rANS already models significant bits and value tables in two passes. Quick mode is single-pass QOI-style packet coding (>1 GB/s) with no rANS tables: adding per-unit high/low byte-plane inspection (--quick-bits packets) lets Quick mode collapse constant zero LSB planes (shifted 10/12/14-bit sensors) or equal MSB==LSB planes (replicated 8→16-bit) to a 1-byte header (2.0× smaller).

Feature 26 / Record 37 · Unit Ordinals

2-RTT Verified HTTP Region Access

Splitting stripes into 64-px column groups enables fine 2D ROI reads via the trailing uTAB hint table. Prefixing each unit record with its 0-based LEB128 ordinal (--unit-ordinals on) lets region readers verify fetched spans locally in 2 HTTP requests instead of 352 (+0.02% file size).