Changes
- Improved four-level grayscale on EPUB image pages by using the X4 factory waveform in Auto refresh mode, with strip-streamed dual-plane rendering, calibrated dithering, and adaptive JPEG tone mapping (adapted from PR #169 by
erickosanchezj, revision9dbdde6e). - Kept forced refresh modes and low-memory fallback on the previous differential calibration, versioned waveform-specific pixel caches, and rebuilt the BW page when factory backup allocation fails so a factory-calibrated cache is never displayed through the differential path.
- Preserved highlights, white text, small caps, superscripts, and subscripts in the absolute grayscale pass; bounded error diffusion and made optimized fills safe for both grayscale planes.
- Passed all 218 host regressions plus
defaultandgh_releaseESP32-C3 builds. Release flash is 5,687,043 / 6,553,600 bytes (86.8%); X4 panel appearance, transitions, orientations, and fault-injected low-memory fallback still require physical validation. X4 Pro remains unsupported and explicitly blocked by Auto Flash.