| /* |
| * jcparam.c |
| * |
| * This file was part of the Independent JPEG Group's software: |
| * Copyright (C) 1991-1998, Thomas G. Lane. |
| * Modified 2003-2008 by Guido Vollbeding. |
| * Lossless JPEG Modifications: |
| * Copyright (C) 1999, Ken Murchison. |
| * libjpeg-turbo Modifications: |
| * Copyright (C) 2009-2011, 2018, 2023, D. R. Commander. |
| * For conditions of distribution and use, see the accompanying README.ijg |
| * file. |
| * |
| * This file contains optional default-setting code for the JPEG compressor. |
| * Applications do not have to use this file, but those that don't use it |
| * must know a lot more about the innards of the JPEG code. |
| */ |
| |
| #define JPEG_INTERNALS |
| #include "jinclude.h" |
| #include "jpeglib.h" |
| #include "jstdhuff.c" |
| |
| |
| /* |
| * Quantization table setup routines |
| */ |
| |
| GLOBAL(void) |
| jpeg_add_quant_table(j_compress_ptr cinfo, int which_tbl, |
| const unsigned int *basic_table, int scale_factor, |
| boolean force_baseline) |
| /* Define a quantization table equal to the basic_table times |
| * a scale factor (given as a percentage). |
| * If force_baseline is TRUE, the computed quantization table entries |
| * are limited to 1..255 for JPEG baseline compatibility. |
| */ |
| { |
| JQUANT_TBL **qtblptr; |
| int i; |
| long temp; |
| |
| /* Safety check to ensure start_compress not called yet. */ |
| if (cinfo->global_state != CSTATE_START) |
| ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| |
| if (which_tbl < 0 || which_tbl >= NUM_QUANT_TBLS) |
| ERREXIT1(cinfo, JERR_DQT_INDEX, which_tbl); |
| |
| qtblptr = &cinfo->quant_tbl_ptrs[which_tbl]; |
| |
| if (*qtblptr == NULL) |
| *qtblptr = jpeg_alloc_quant_table((j_common_ptr)cinfo); |
| |
| for (i = 0; i < DCTSIZE2; i++) { |
| temp = ((long)basic_table[i] * scale_factor + 50L) / 100L; |
| /* limit the values to the valid range */ |
| if (temp <= 0L) temp = 1L; |
| if (temp > 32767L) temp = 32767L; /* max quantizer needed for 12 bits */ |
| if (force_baseline && temp > 255L) |
| temp = 255L; /* limit to baseline range if requested */ |
| (*qtblptr)->quantval[i] = (UINT16)temp; |
| } |
| |
| /* Initialize sent_table FALSE so table will be written to JPEG file. */ |
| (*qtblptr)->sent_table = FALSE; |
| } |
| |
| |
| /* These are the sample quantization tables given in Annex K (Clause K.1) of |
| * Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994. |
| * The spec says that the values given produce "good" quality, and |
| * when divided by 2, "very good" quality. |
| */ |
| static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = { |
| 16, 11, 10, 16, 24, 40, 51, 61, |
| 12, 12, 14, 19, 26, 58, 60, 55, |
| 14, 13, 16, 24, 40, 57, 69, 56, |
| 14, 17, 22, 29, 51, 87, 80, 62, |
| 18, 22, 37, 56, 68, 109, 103, 77, |
| 24, 35, 55, 64, 81, 104, 113, 92, |
| 49, 64, 78, 87, 103, 121, 120, 101, |
| 72, 92, 95, 98, 112, 100, 103, 99 |
| }; |
| static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = { |
| 17, 18, 24, 47, 99, 99, 99, 99, |
| 18, 21, 26, 66, 99, 99, 99, 99, |
| 24, 26, 56, 99, 99, 99, 99, 99, |
| 47, 66, 99, 99, 99, 99, 99, 99, |
| 99, 99, 99, 99, 99, 99, 99, 99, |
| 99, 99, 99, 99, 99, 99, 99, 99, |
| 99, 99, 99, 99, 99, 99, 99, 99, |
| 99, 99, 99, 99, 99, 99, 99, 99 |
| }; |
| |
| |
| #if JPEG_LIB_VERSION >= 70 |
| GLOBAL(void) |
| jpeg_default_qtables(j_compress_ptr cinfo, boolean force_baseline) |
| /* Set or change the 'quality' (quantization) setting, using default tables |
| * and straight percentage-scaling quality scales. |
| * This entry point allows different scalings for luminance and chrominance. |
| */ |
| { |
| /* Set up two quantization tables using the specified scaling */ |
| jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl, |
| cinfo->q_scale_factor[0], force_baseline); |
| jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl, |
| cinfo->q_scale_factor[1], force_baseline); |
| } |
| #endif |
| |
| |
| GLOBAL(void) |
| jpeg_set_linear_quality(j_compress_ptr cinfo, int scale_factor, |
| boolean force_baseline) |
| /* Set or change the 'quality' (quantization) setting, using default tables |
| * and a straight percentage-scaling quality scale. In most cases it's better |
| * to use jpeg_set_quality (below); this entry point is provided for |
| * applications that insist on a linear percentage scaling. |
| */ |
| { |
| /* Set up two quantization tables using the specified scaling */ |
| jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl, |
| scale_factor, force_baseline); |
| jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl, |
| scale_factor, force_baseline); |
| } |
| |
| |
| GLOBAL(int) |
| jpeg_quality_scaling(int quality) |
| /* Convert a user-specified quality rating to a percentage scaling factor |
| * for an underlying quantization table, using our recommended scaling curve. |
| * The input 'quality' factor should be 0 (terrible) to 100 (very good). |
| */ |
| { |
| /* Safety limit on quality factor. Convert 0 to 1 to avoid zero divide. */ |
| if (quality <= 0) quality = 1; |
| if (quality > 100) quality = 100; |
| |
| /* The basic table is used as-is (scaling 100) for a quality of 50. |
| * Qualities 50..100 are converted to scaling percentage 200 - 2*Q; |
| * note that at Q=100 the scaling is 0, which will cause jpeg_add_quant_table |
| * to make all the table entries 1 (hence, minimum quantization loss). |
| * Qualities 1..50 are converted to scaling percentage 5000/Q. |
| */ |
| if (quality < 50) |
| quality = 5000 / quality; |
| else |
| quality = 200 - quality * 2; |
| |
| return quality; |
| } |
| |
| |
| GLOBAL(void) |
| jpeg_set_quality(j_compress_ptr cinfo, int quality, boolean force_baseline) |
| /* Set or change the 'quality' (quantization) setting, using default tables. |
| * This is the standard quality-adjusting entry point for typical user |
| * interfaces; only those who want detailed control over quantization tables |
| * would use the preceding three routines directly. |
| */ |
| { |
| /* Convert user 0-100 rating to percentage scaling */ |
| quality = jpeg_quality_scaling(quality); |
| |
| /* Set up standard quality tables */ |
| jpeg_set_linear_quality(cinfo, quality, force_baseline); |
| } |
| |
| |
| /* |
| * Default parameter setup for compression. |
| * |
| * Applications that don't choose to use this routine must do their |
| * own setup of all these parameters. Alternately, you can call this |
| * to establish defaults and then alter parameters selectively. This |
| * is the recommended approach since, if we add any new parameters, |
| * your code will still work (they'll be set to reasonable defaults). |
| */ |
| |
| GLOBAL(void) |
| jpeg_set_defaults(j_compress_ptr cinfo) |
| { |
| int i; |
| |
| /* Safety check to ensure start_compress not called yet. */ |
| if (cinfo->global_state != CSTATE_START) |
| ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| |
| /* Allocate comp_info array large enough for maximum component count. |
| * Array is made permanent in case application wants to compress |
| * multiple images at same param settings. |
| */ |
| if (cinfo->comp_info == NULL) |
| cinfo->comp_info = (jpeg_component_info *) |
| (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT, |
| MAX_COMPONENTS * sizeof(jpeg_component_info)); |
| |
| /* Initialize everything not dependent on the color space */ |
| |
| #if JPEG_LIB_VERSION >= 70 |
| cinfo->scale_num = 1; /* 1:1 scaling */ |
| cinfo->scale_denom = 1; |
| #endif |
| /* Set up two quantization tables using default quality of 75 */ |
| jpeg_set_quality(cinfo, 75, TRUE); |
| /* Set up two Huffman tables */ |
| std_huff_tables((j_common_ptr)cinfo); |
| |
| /* Initialize default arithmetic coding conditioning */ |
| for (i = 0; i < NUM_ARITH_TBLS; i++) { |
| cinfo->arith_dc_L[i] = 0; |
| cinfo->arith_dc_U[i] = 1; |
| cinfo->arith_ac_K[i] = 5; |
| } |
| |
| /* Default is no multiple-scan output */ |
| cinfo->scan_info = NULL; |
| cinfo->num_scans = 0; |
| |
| /* Expect normal source image, not raw downsampled data */ |
| cinfo->raw_data_in = FALSE; |
| |
| /* Use Huffman coding, not arithmetic coding, by default */ |
| cinfo->arith_code = FALSE; |
| |
| /* By default, don't do extra passes to optimize entropy coding */ |
| cinfo->optimize_coding = FALSE; |
| /* The standard Huffman tables are only valid for 8-bit data precision. |
| * If the precision is higher, force optimization on so that usable |
| * tables will be computed. This test can be removed if default tables |
| * are supplied that are valid for the desired precision. |
| */ |
| if (cinfo->data_precision == 12 && !cinfo->arith_code) |
| cinfo->optimize_coding = TRUE; |
| |
| /* By default, use the simpler non-cosited sampling alignment */ |
| cinfo->CCIR601_sampling = FALSE; |
| |
| #if JPEG_LIB_VERSION >= 70 |
| /* By default, apply fancy downsampling */ |
| cinfo->do_fancy_downsampling = TRUE; |
| #endif |
| |
| /* No input smoothing */ |
| cinfo->smoothing_factor = 0; |
| |
| /* DCT algorithm preference */ |
| cinfo->dct_method = JDCT_DEFAULT; |
| |
| /* No restart markers */ |
| cinfo->restart_interval = 0; |
| cinfo->restart_in_rows = 0; |
| |
| /* Fill in default JFIF marker parameters. Note that whether the marker |
| * will actually be written is determined by jpeg_set_colorspace. |
| * |
| * By default, the library emits JFIF version code 1.01. |
| * An application that wants to emit JFIF 1.02 extension markers should set |
| * JFIF_minor_version to 2. We could probably get away with just defaulting |
| * to 1.02, but there may still be some decoders in use that will complain |
| * about that; saying 1.01 should minimize compatibility problems. |
| */ |
| cinfo->JFIF_major_version = 1; /* Default JFIF version = 1.01 */ |
| cinfo->JFIF_minor_version = 1; |
| cinfo->density_unit = 0; /* Pixel size is unknown by default */ |
| cinfo->X_density = 1; /* Pixel aspect ratio is square by default */ |
| cinfo->Y_density = 1; |
| |
| /* Choose JPEG colorspace based on input space, set defaults accordingly */ |
| |
| jpeg_default_colorspace(cinfo); |
| } |
| |
| |
| /* |
| * Select an appropriate JPEG colorspace for in_color_space. |
| */ |
| |
| GLOBAL(void) |
| jpeg_default_colorspace(j_compress_ptr cinfo) |
| { |
| switch (cinfo->in_color_space) { |
| case JCS_GRAYSCALE: |
| jpeg_set_colorspace(cinfo, JCS_GRAYSCALE); |
| break; |
| case JCS_RGB: |
| case JCS_EXT_RGB: |
| case JCS_EXT_RGBX: |
| case JCS_EXT_BGR: |
| case JCS_EXT_BGRX: |
| case JCS_EXT_XBGR: |
| case JCS_EXT_XRGB: |
| case JCS_EXT_RGBA: |
| case JCS_EXT_BGRA: |
| case JCS_EXT_ABGR: |
| case JCS_EXT_ARGB: |
| if (cinfo->master->lossless) |
| jpeg_set_colorspace(cinfo, JCS_RGB); |
| else |
| jpeg_set_colorspace(cinfo, JCS_YCbCr); |
| break; |
| case JCS_YCbCr: |
| jpeg_set_colorspace(cinfo, JCS_YCbCr); |
| break; |
| case JCS_CMYK: |
| jpeg_set_colorspace(cinfo, JCS_CMYK); /* By default, no translation */ |
| break; |
| case JCS_YCCK: |
| jpeg_set_colorspace(cinfo, JCS_YCCK); |
| break; |
| case JCS_UNKNOWN: |
| jpeg_set_colorspace(cinfo, JCS_UNKNOWN); |
| break; |
| default: |
| ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); |
| } |
| } |
| |
| |
| /* |
| * Set the JPEG colorspace, and choose colorspace-dependent default values. |
| */ |
| |
| GLOBAL(void) |
| jpeg_set_colorspace(j_compress_ptr cinfo, J_COLOR_SPACE colorspace) |
| { |
| jpeg_component_info *compptr; |
| int ci; |
| |
| #define SET_COMP(index, id, hsamp, vsamp, quant, dctbl, actbl) \ |
| (compptr = &cinfo->comp_info[index], \ |
| compptr->component_id = (id), \ |
| compptr->h_samp_factor = (hsamp), \ |
| compptr->v_samp_factor = (vsamp), \ |
| compptr->quant_tbl_no = (quant), \ |
| compptr->dc_tbl_no = (dctbl), \ |
| compptr->ac_tbl_no = (actbl) ) |
| |
| /* Safety check to ensure start_compress not called yet. */ |
| if (cinfo->global_state != CSTATE_START) |
| ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| |
| /* For all colorspaces, we use Q and Huff tables 0 for luminance components, |
| * tables 1 for chrominance components. |
| */ |
| |
| cinfo->jpeg_color_space = colorspace; |
| |
| cinfo->write_JFIF_header = FALSE; /* No marker for non-JFIF colorspaces */ |
| cinfo->write_Adobe_marker = FALSE; /* write no Adobe marker by default */ |
| |
| switch (colorspace) { |
| case JCS_GRAYSCALE: |
| cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */ |
| cinfo->num_components = 1; |
| /* JFIF specifies component ID 1 */ |
| SET_COMP(0, 1, 1, 1, 0, 0, 0); |
| break; |
| case JCS_RGB: |
| cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag RGB */ |
| cinfo->num_components = 3; |
| SET_COMP(0, 0x52 /* 'R' */, 1, 1, 0, 0, 0); |
| SET_COMP(1, 0x47 /* 'G' */, 1, 1, 0, 0, 0); |
| SET_COMP(2, 0x42 /* 'B' */, 1, 1, 0, 0, 0); |
| break; |
| case JCS_YCbCr: |
| cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */ |
| cinfo->num_components = 3; |
| /* JFIF specifies component IDs 1,2,3 */ |
| /* We default to 2x2 subsamples of chrominance */ |
| SET_COMP(0, 1, 2, 2, 0, 0, 0); |
| SET_COMP(1, 2, 1, 1, 1, 1, 1); |
| SET_COMP(2, 3, 1, 1, 1, 1, 1); |
| break; |
| case JCS_CMYK: |
| cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag CMYK */ |
| cinfo->num_components = 4; |
| SET_COMP(0, 0x43 /* 'C' */, 1, 1, 0, 0, 0); |
| SET_COMP(1, 0x4D /* 'M' */, 1, 1, 0, 0, 0); |
| SET_COMP(2, 0x59 /* 'Y' */, 1, 1, 0, 0, 0); |
| SET_COMP(3, 0x4B /* 'K' */, 1, 1, 0, 0, 0); |
| break; |
| case JCS_YCCK: |
| cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag YCCK */ |
| cinfo->num_components = 4; |
| SET_COMP(0, 1, 2, 2, 0, 0, 0); |
| SET_COMP(1, 2, 1, 1, 1, 1, 1); |
| SET_COMP(2, 3, 1, 1, 1, 1, 1); |
| SET_COMP(3, 4, 2, 2, 0, 0, 0); |
| break; |
| case JCS_UNKNOWN: |
| cinfo->num_components = cinfo->input_components; |
| if (cinfo->num_components < 1 || cinfo->num_components > MAX_COMPONENTS) |
| ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components, |
| MAX_COMPONENTS); |
| for (ci = 0; ci < cinfo->num_components; ci++) { |
| SET_COMP(ci, ci, 1, 1, 0, 0, 0); |
| } |
| break; |
| default: |
| ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); |
| } |
| } |
| |
| |
| #ifdef C_PROGRESSIVE_SUPPORTED |
| |
| LOCAL(jpeg_scan_info *) |
| fill_a_scan(jpeg_scan_info *scanptr, int ci, int Ss, int Se, int Ah, int Al) |
| /* Support routine: generate one scan for specified component */ |
| { |
| scanptr->comps_in_scan = 1; |
| scanptr->component_index[0] = ci; |
| scanptr->Ss = Ss; |
| scanptr->Se = Se; |
| scanptr->Ah = Ah; |
| scanptr->Al = Al; |
| scanptr++; |
| return scanptr; |
| } |
| |
| LOCAL(jpeg_scan_info *) |
| fill_scans(jpeg_scan_info *scanptr, int ncomps, int Ss, int Se, int Ah, int Al) |
| /* Support routine: generate one scan for each component */ |
| { |
| int ci; |
| |
| for (ci = 0; ci < ncomps; ci++) { |
| scanptr->comps_in_scan = 1; |
| scanptr->component_index[0] = ci; |
| scanptr->Ss = Ss; |
| scanptr->Se = Se; |
| scanptr->Ah = Ah; |
| scanptr->Al = Al; |
| scanptr++; |
| } |
| return scanptr; |
| } |
| |
| LOCAL(jpeg_scan_info *) |
| fill_dc_scans(jpeg_scan_info *scanptr, int ncomps, int Ah, int Al) |
| /* Support routine: generate interleaved DC scan if possible, else N scans */ |
| { |
| int ci; |
| |
| if (ncomps <= MAX_COMPS_IN_SCAN) { |
| /* Single interleaved DC scan */ |
| scanptr->comps_in_scan = ncomps; |
| for (ci = 0; ci < ncomps; ci++) |
| scanptr->component_index[ci] = ci; |
| scanptr->Ss = scanptr->Se = 0; |
| scanptr->Ah = Ah; |
| scanptr->Al = Al; |
| scanptr++; |
| } else { |
| /* Noninterleaved DC scan for each component */ |
| scanptr = fill_scans(scanptr, ncomps, 0, 0, Ah, Al); |
| } |
| return scanptr; |
| } |
| |
| |
| /* |
| * Create a recommended progressive-JPEG script. |
| * cinfo->num_components and cinfo->jpeg_color_space must be correct. |
| */ |
| |
| GLOBAL(void) |
| jpeg_simple_progression(j_compress_ptr cinfo) |
| { |
| int ncomps = cinfo->num_components; |
| int nscans; |
| jpeg_scan_info *scanptr; |
| |
| /* Safety check to ensure start_compress not called yet. */ |
| if (cinfo->global_state != CSTATE_START) |
| ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| |
| if (cinfo->master->lossless) { |
| cinfo->master->lossless = FALSE; |
| jpeg_default_colorspace(cinfo); |
| } |
| |
| /* Figure space needed for script. Calculation must match code below! */ |
| if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) { |
| /* Custom script for YCbCr color images. */ |
| nscans = 10; |
| } else { |
| /* All-purpose script for other color spaces. */ |
| if (ncomps > MAX_COMPS_IN_SCAN) |
| nscans = 6 * ncomps; /* 2 DC + 4 AC scans per component */ |
| else |
| nscans = 2 + 4 * ncomps; /* 2 DC scans; 4 AC scans per component */ |
| } |
| |
| /* Allocate space for script. |
| * We need to put it in the permanent pool in case the application performs |
| * multiple compressions without changing the settings. To avoid a memory |
| * leak if jpeg_simple_progression is called repeatedly for the same JPEG |
| * object, we try to re-use previously allocated space, and we allocate |
| * enough space to handle YCbCr even if initially asked for grayscale. |
| */ |
| if (cinfo->script_space == NULL || cinfo->script_space_size < nscans) { |
| cinfo->script_space_size = MAX(nscans, 10); |
| cinfo->script_space = (jpeg_scan_info *) |
| (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT, |
| cinfo->script_space_size * sizeof(jpeg_scan_info)); |
| } |
| scanptr = cinfo->script_space; |
| cinfo->scan_info = scanptr; |
| cinfo->num_scans = nscans; |
| |
| if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) { |
| /* Custom script for YCbCr color images. */ |
| /* Initial DC scan */ |
| scanptr = fill_dc_scans(scanptr, ncomps, 0, 1); |
| /* Initial AC scan: get some luma data out in a hurry */ |
| scanptr = fill_a_scan(scanptr, 0, 1, 5, 0, 2); |
| /* Chroma data is too small to be worth expending many scans on */ |
| scanptr = fill_a_scan(scanptr, 2, 1, 63, 0, 1); |
| scanptr = fill_a_scan(scanptr, 1, 1, 63, 0, 1); |
| /* Complete spectral selection for luma AC */ |
| scanptr = fill_a_scan(scanptr, 0, 6, 63, 0, 2); |
| /* Refine next bit of luma AC */ |
| scanptr = fill_a_scan(scanptr, 0, 1, 63, 2, 1); |
| /* Finish DC successive approximation */ |
| scanptr = fill_dc_scans(scanptr, ncomps, 1, 0); |
| /* Finish AC successive approximation */ |
| scanptr = fill_a_scan(scanptr, 2, 1, 63, 1, 0); |
| scanptr = fill_a_scan(scanptr, 1, 1, 63, 1, 0); |
| /* Luma bottom bit comes last since it's usually largest scan */ |
| scanptr = fill_a_scan(scanptr, 0, 1, 63, 1, 0); |
| } else { |
| /* All-purpose script for other color spaces. */ |
| /* Successive approximation first pass */ |
| scanptr = fill_dc_scans(scanptr, ncomps, 0, 1); |
| scanptr = fill_scans(scanptr, ncomps, 1, 5, 0, 2); |
| scanptr = fill_scans(scanptr, ncomps, 6, 63, 0, 2); |
| /* Successive approximation second pass */ |
| scanptr = fill_scans(scanptr, ncomps, 1, 63, 2, 1); |
| /* Successive approximation final pass */ |
| scanptr = fill_dc_scans(scanptr, ncomps, 1, 0); |
| scanptr = fill_scans(scanptr, ncomps, 1, 63, 1, 0); |
| } |
| } |
| |
| #endif /* C_PROGRESSIVE_SUPPORTED */ |
| |
| |
| #ifdef C_LOSSLESS_SUPPORTED |
| |
| /* |
| * Enable lossless mode. |
| */ |
| |
| GLOBAL(void) |
| jpeg_enable_lossless(j_compress_ptr cinfo, int predictor_selection_value, |
| int point_transform) |
| { |
| /* Safety check to ensure start_compress not called yet. */ |
| if (cinfo->global_state != CSTATE_START) |
| ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
| |
| cinfo->master->lossless = TRUE; |
| cinfo->Ss = predictor_selection_value; |
| cinfo->Se = 0; |
| cinfo->Ah = 0; |
| cinfo->Al = point_transform; |
| |
| /* The JPEG spec simply gives the range 0..15 for Al (Pt), but that seems |
| * wrong: the upper bound ought to depend on data precision. Perhaps they |
| * really meant 0..N-1 for N-bit precision, which is what we allow here. |
| * Values greater than or equal to the data precision will result in a blank |
| * image. |
| */ |
| if (cinfo->Ss < 1 || cinfo->Ss > 7 || |
| cinfo->Al < 0 || cinfo->Al >= cinfo->data_precision) |
| ERREXIT4(cinfo, JERR_BAD_PROGRESSION, |
| cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al); |
| } |
| |
| #endif /* C_LOSSLESS_SUPPORTED */ |