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BIC v0.2.0

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@github-actions github-actions released this 21 Oct 00:56
· 13 commits to main since this release
v0.2.0
0955920

The BIC2 format replaces BIC1, and BIC1 files can no longer be read. Re-encode
them from the original images.

BIC targets images with large solid areas: screenshots, UI, diagrams,
charts, icons and pixel art. It offers little or no advantage on photographs.
JPEG sources are stored unchanged.

Added

  • BIC2 coding:
    • a palette for images with up to 256 colors;
    • a subtract-green color transform;
    • row prediction, either fixed (none or up) or chosen per row (none, left,
      up, average, Paeth, MED).
  • Exhaustive encoder: it tries every transform and predictor combination
    in parallel and keeps the smallest. The default Zstandard level is now 19.
  • Near-lossless mode (--max-error N) in the style of JPEG-LS: every
    decoded sample is within N of the original. Lossless candidates are tried
    too, so flat graphics stay exact.
  • Original-file storage: a PNG, JPEG, WebP or HEIF source that is smaller
    than BIC's own encoding is stored unchanged, so a .bic file is never larger
    than its original plus 32 bytes. --transcode disables this.
  • ICC profiles are stored in the container and written back to PNG
    output.
  • EXIF orientation is applied when reading sources.
  • --fast-decode: skips per-row prediction for faster opening, at the cost
    of slightly larger photographs.
  • bic-view, a viewer without a console window:
    • File > Open (Ctrl+O) and File > Save as BIC (Ctrl+S), with saving in the
      background;
    • smooth resampling when the window is resized;
    • errors shown in a dialog;
    • used by the Windows file association.
  • bic compare: benchmarks against PNG, oxipng, WebP lossless and QOI on
    files or folders, with CSV output and PSNR for near-lossless runs.
  • bic verify --max-error for checking near-lossless files.
  • Library API: encode_file, encode_source, read_source,
    encode_rgba_with_metadata, decode_with_metadata, storage, and
    DecodeLimits for untrusted input.
  • cli feature (on by default) for the programs. With
    default-features = false the library depends only on anyhow, image,
    heic-rs and zstd.
  • Testing: property-based tests and cargo-fuzz targets. CI runs on Linux
    and Windows, with fuzzing and a synthetic-corpus benchmark.

Changed

  • On the project's benchmarks (geometric mean against oxipng), flat graphics
    went from 1.316 to 0.755. Lossless photographs went from 1.849 to 0.837, but
    that comparison excludes strong photographic codecs.
  • Lossless decoding processes whole rows with vectorizable loops.
  • The decoder's default memory limit is 512 MiB, set with --max-alloc-mib.

Removed

  • --quant-step, --smooth-tolerance and --residual, replaced by
    --max-error.
  • is_png_fallback, replaced by storage.

Fixed

  • Block partitioning only ever used 256-sample blocks.
  • A malformed file with an inverted channel range could crash the decoder.
  • Payloads that decompressed past their declared size were not rejected.
  • Encoding an empty image with --png-fallback failed.
  • Decoding to JPEG failed on RGBA images.
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