jcicc.c (4072B)
1 /* 2 * jcicc.c 3 * 4 * Copyright (C) 1997-1998, Thomas G. Lane, Todd Newman. 5 * Copyright (C) 2017, D. R. Commander. 6 * For conditions of distribution and use, see the accompanying README.ijg 7 * file. 8 * 9 * This file provides code to write International Color Consortium (ICC) device 10 * profiles embedded in JFIF JPEG image files. The ICC has defined a standard 11 * for including such data in JPEG "APP2" markers. The code given here does 12 * not know anything about the internal structure of the ICC profile data; it 13 * just knows how to embed the profile data in a JPEG file while writing it. 14 */ 15 16 #define JPEG_INTERNALS 17 #include "jinclude.h" 18 #include "jpeglib.h" 19 #include "jerror.h" 20 21 22 /* 23 * Since an ICC profile can be larger than the maximum size of a JPEG marker 24 * (64K), we need provisions to split it into multiple markers. The format 25 * defined by the ICC specifies one or more APP2 markers containing the 26 * following data: 27 * Identifying string ASCII "ICC_PROFILE\0" (12 bytes) 28 * Marker sequence number 1 for first APP2, 2 for next, etc (1 byte) 29 * Number of markers Total number of APP2's used (1 byte) 30 * Profile data (remainder of APP2 data) 31 * Decoders should use the marker sequence numbers to reassemble the profile, 32 * rather than assuming that the APP2 markers appear in the correct sequence. 33 */ 34 35 #define ICC_MARKER (JPEG_APP0 + 2) /* JPEG marker code for ICC */ 36 #define ICC_OVERHEAD_LEN 14 /* size of non-profile data in APP2 */ 37 #define MAX_BYTES_IN_MARKER 65533 /* maximum data len of a JPEG marker */ 38 #define MAX_DATA_BYTES_IN_MARKER (MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN) 39 40 41 /* 42 * This routine writes the given ICC profile data into a JPEG file. It *must* 43 * be called AFTER calling jpeg_start_compress() and BEFORE the first call to 44 * jpeg_write_scanlines(). (This ordering ensures that the APP2 marker(s) will 45 * appear after the SOI and JFIF or Adobe markers, but before all else.) 46 */ 47 48 GLOBAL(void) 49 jpeg_write_icc_profile(j_compress_ptr cinfo, const JOCTET *icc_data_ptr, 50 unsigned int icc_data_len) 51 { 52 unsigned int num_markers; /* total number of markers we'll write */ 53 int cur_marker = 1; /* per spec, counting starts at 1 */ 54 unsigned int length; /* number of bytes to write in this marker */ 55 56 if (icc_data_ptr == NULL || icc_data_len == 0) 57 ERREXIT(cinfo, JERR_BUFFER_SIZE); 58 if (cinfo->global_state < CSTATE_SCANNING) 59 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 60 61 /* Calculate the number of markers we'll need, rounding up of course */ 62 num_markers = icc_data_len / MAX_DATA_BYTES_IN_MARKER; 63 if (num_markers * MAX_DATA_BYTES_IN_MARKER != icc_data_len) 64 num_markers++; 65 66 while (icc_data_len > 0) { 67 /* length of profile to put in this marker */ 68 length = icc_data_len; 69 if (length > MAX_DATA_BYTES_IN_MARKER) 70 length = MAX_DATA_BYTES_IN_MARKER; 71 icc_data_len -= length; 72 73 /* Write the JPEG marker header (APP2 code and marker length) */ 74 jpeg_write_m_header(cinfo, ICC_MARKER, 75 (unsigned int)(length + ICC_OVERHEAD_LEN)); 76 77 /* Write the marker identifying string "ICC_PROFILE" (null-terminated). We 78 * code it in this less-than-transparent way so that the code works even if 79 * the local character set is not ASCII. 80 */ 81 jpeg_write_m_byte(cinfo, 0x49); 82 jpeg_write_m_byte(cinfo, 0x43); 83 jpeg_write_m_byte(cinfo, 0x43); 84 jpeg_write_m_byte(cinfo, 0x5F); 85 jpeg_write_m_byte(cinfo, 0x50); 86 jpeg_write_m_byte(cinfo, 0x52); 87 jpeg_write_m_byte(cinfo, 0x4F); 88 jpeg_write_m_byte(cinfo, 0x46); 89 jpeg_write_m_byte(cinfo, 0x49); 90 jpeg_write_m_byte(cinfo, 0x4C); 91 jpeg_write_m_byte(cinfo, 0x45); 92 jpeg_write_m_byte(cinfo, 0x0); 93 94 /* Add the sequencing info */ 95 jpeg_write_m_byte(cinfo, cur_marker); 96 jpeg_write_m_byte(cinfo, (int)num_markers); 97 98 /* Add the profile data */ 99 while (length--) { 100 jpeg_write_m_byte(cinfo, *icc_data_ptr); 101 icc_data_ptr++; 102 } 103 cur_marker++; 104 } 105 }