The CAS (Contrast Adaptive Sharpening) post-filter initialized its output buffer to zero instead of copying the input. Since the filter loop skips the outermost row and column (for y in 1..h-1), border pixels remained at 0 = black. Every decoded image had a 1-pixel black frame on all four sides.

Fix: postprocess.rs:apply_cas_sharpening — vec![0.0; n] replaced by input.to_vec(). Border pixels now pass through unchanged.

Tree canopy artifact (mixed-block halo)

At the interface between dark foliage and bright sky, 16x16 LOT blocks straddling both regions produced a visible grayish rectangular halo. The block's DC averages dark+bright content, and quantized AC coefficients cannot fully restore the high-contrast transition within the block.

Fix (two layers):

Gas-only deblocking (dsp::deblock_gas_only) added to v12 decoder. Smooths block boundaries where both sides are smooth (sky/sky), using Weber-adaptive blending (stronger in dark zones). Does not touch edges (tree contours are classified as "solid" and left intact).
Anti-ring sigma filter (dsp::anti_ring_sigma) added to v12 decoder. A 7x7 sigma filter applied near detected edges: for each pixel in an edge zone, computes the mean of nearby pixels within a luminance-adaptive tolerance. Sky pixels pulled toward gray by the mixed-block DC are corrected back toward the true sky value, because dark tree pixels fall outside the sigma tolerance and are excluded from the average.

Both filters are decoder-only (zero bitstream cost) and improve PSNR by +0.1-0.2 dB on average.

v12 promoted to default pipeline

The CLI (aurea encode) previously used the v3 LOT encoder. Switched to v12 which includes Turing morphogenesis, CfL prediction, rANS v12 Exp-Golomb, and all overhead optimizations. On the user's test image (1920x1280): -19% file size, +1.26 dB PSNR compared to v3 at the same quality setting.

Benchmark results

Kodak 24 (768x512, standard benchmark):

Metric	Value
BD-Rate vs JPEG	-6.0%
Images won	22/24
Best	kodim23 -15.3%

HD images (2560x1440+, 6 images):

Metric	Value
BD-Rate vs JPEG	-16.9%
Images won	6/6
Best	agree -31.7%

Trashland restored

The satellite signal loss simulator (aurea-trashland) was broken (stub todo!()). Rewired to use the v12 encode/decode pipeline. Five progressive corruption layers: macroblocking → chroma glitch → line desync → freeze blocks → pixel explosion.

Full Changelog: v0.3.0...v0.3.1

Assets 3