code wiki / _hdl_build / nx_jpeg_color_write.nx

nx_jpeg_color_write.nx

buildroot/runtime/_hdl_build/nx_jpeg_color_write.nx

6960 B115 linesdepth 6pulls 9 transitivereach 8 importersview sourcekind librarytopic jpeg
docsdependenciesstructsconstsfunctions

about

nx_jpeg_color_write.nx -- SOVEREIGN baseline COLOR (YCbCr 4:4:4) JFIF writer. Extends the grayscale J3 writer (nx_jpeg_write) to 3 components so photo thumbnails encode as real .jpg (far smaller than lossless PNG). 2 DQT (luma id0 + chroma id1, via nx_qt_luma/nx_qt_chroma), 3-component SOF0/SOS, interleaved MCUs (one 8x8 block per component, no chroma subsampling). REUSES (DRY): jw_b/jw_u16/jw_qround + nx_dct8 + nx_zigzag + nx_jpeg_block_enc + nx_jpeg_huff_enc, sharing the LUMA DC/AC Huffman tables across all three components (valid baseline -- table choice is the encoder's; the chroma compression win is the quant table). RGB->YCbCr is the standard 8-bit-integer fast transform (NO floats). W,H must be multiples of 8. JPEG/Annex K public since 1992 -> patent-clean. license_tier: ORIGINAL

dependencies 8 imports · 7 importers

nx_syscalls.nx nx_h264_bitwriter.nx nx_dct8.nx nx_quant_table.nx nx_zigzag.nx nx_jpeg_huff_enc.nx nx_jpeg_block_enc.nx nx_jpeg_write.nx nx_jpeg_color_write.nx nx_cam_poster.nx nx_galx_thumb_oneshot.nx nx_jpeg_color_write_gate.nx nx_reader_panels_gate.nx nx_reader_tile.nx nx_reader_tile_gate.nx nx_reader_zoomserve_gate.nx

imports: nx_syscalls.nxnx_h264_bitwriter.nxnx_dct8.nxnx_quant_table.nxnx_zigzag.nxnx_jpeg_huff_enc.nxnx_jpeg_block_enc.nxnx_jpeg_write.nx

imported by: nx_cam_poster.nxnx_galx_thumb_oneshot.nxnx_jpeg_color_write_gate.nxnx_reader_panels_gate.nxnx_reader_tile.nxnx_reader_tile_gate.nxnx_reader_zoomserve_gate.nx

structs

none

consts

17const K_MAGIC_4096: i64 = 4096

functions

20func jcw_y(r: i64, g: i64, b: i64) -> i64 { var v: i64 = (77*r + 150*g + 29*b) >> 8; if v < 0 { v = 0 } if v > 255 { v = 255 } return v }
called by 1: jcw_write_color
21func jcw_cb(r: i64, g: i64, b: i64) -> i64 { var v: i64 = (((0-43)*r - 85*g + 128*b) >> 8) + 128; if v < 0 { v = 0 } if v > 255 { v = 255 } return v }
called by 1: jcw_write_color
22func jcw_cr(r: i64, g: i64, b: i64) -> i64 { var v: i64 = ((128*r - 107*g - 21*b) >> 8) + 128; if v < 0 { v = 0 } if v > 255 { v = 255 } return v }
called by 1: jcw_write_color
26func jcw_block(bw: *BitWriter, plane: *i64, W: i64, bx: i64, by: i64, qt: *i64,
called by 1: jcw_write_color calls 4: nx_dct8_forward_2djw_qroundnx_zigzag_scanjbe_encode_block
41func jcw_write_color(out: *u8, W: i64, H: i64, rgb: *u8,
called by 7: encode_jpegmainmainmainrt_emitmain+1 calls 9: sys_mmapjcw_yjcw_cbjcw_crjw_bjw_u16+3