jcicc.c 4.0 KB

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  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. #define JPEG_INTERNALS
  16. #include "jinclude.h"
  17. #include "jpeglib.h"
  18. #include "jerror.h"
  19. /*
  20. * Since an ICC profile can be larger than the maximum size of a JPEG marker
  21. * (64K), we need provisions to split it into multiple markers. The format
  22. * defined by the ICC specifies one or more APP2 markers containing the
  23. * following data:
  24. * Identifying string ASCII "ICC_PROFILE\0" (12 bytes)
  25. * Marker sequence number 1 for first APP2, 2 for next, etc (1 byte)
  26. * Number of markers Total number of APP2's used (1 byte)
  27. * Profile data (remainder of APP2 data)
  28. * Decoders should use the marker sequence numbers to reassemble the profile,
  29. * rather than assuming that the APP2 markers appear in the correct sequence.
  30. */
  31. #define ICC_MARKER (JPEG_APP0 + 2) /* JPEG marker code for ICC */
  32. #define ICC_OVERHEAD_LEN 14 /* size of non-profile data in APP2 */
  33. #define MAX_BYTES_IN_MARKER 65533 /* maximum data len of a JPEG marker */
  34. #define MAX_DATA_BYTES_IN_MARKER (MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN)
  35. /*
  36. * This routine writes the given ICC profile data into a JPEG file. It *must*
  37. * be called AFTER calling jpeg_start_compress() and BEFORE the first call to
  38. * jpeg_write_scanlines(). (This ordering ensures that the APP2 marker(s) will
  39. * appear after the SOI and JFIF or Adobe markers, but before all else.)
  40. */
  41. GLOBAL(void)
  42. jpeg_write_icc_profile(j_compress_ptr cinfo, const JOCTET *icc_data_ptr,
  43. unsigned int icc_data_len)
  44. {
  45. unsigned int num_markers; /* total number of markers we'll write */
  46. int cur_marker = 1; /* per spec, counting starts at 1 */
  47. unsigned int length; /* number of bytes to write in this marker */
  48. if (icc_data_ptr == NULL || icc_data_len == 0)
  49. ERREXIT(cinfo, JERR_BUFFER_SIZE);
  50. if (cinfo->global_state < CSTATE_SCANNING)
  51. ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  52. /* Calculate the number of markers we'll need, rounding up of course */
  53. num_markers = icc_data_len / MAX_DATA_BYTES_IN_MARKER;
  54. if (num_markers * MAX_DATA_BYTES_IN_MARKER != icc_data_len)
  55. num_markers++;
  56. while (icc_data_len > 0) {
  57. /* length of profile to put in this marker */
  58. length = icc_data_len;
  59. if (length > MAX_DATA_BYTES_IN_MARKER)
  60. length = MAX_DATA_BYTES_IN_MARKER;
  61. icc_data_len -= length;
  62. /* Write the JPEG marker header (APP2 code and marker length) */
  63. jpeg_write_m_header(cinfo, ICC_MARKER,
  64. (unsigned int)(length + ICC_OVERHEAD_LEN));
  65. /* Write the marker identifying string "ICC_PROFILE" (null-terminated). We
  66. * code it in this less-than-transparent way so that the code works even if
  67. * the local character set is not ASCII.
  68. */
  69. jpeg_write_m_byte(cinfo, 0x49);
  70. jpeg_write_m_byte(cinfo, 0x43);
  71. jpeg_write_m_byte(cinfo, 0x43);
  72. jpeg_write_m_byte(cinfo, 0x5F);
  73. jpeg_write_m_byte(cinfo, 0x50);
  74. jpeg_write_m_byte(cinfo, 0x52);
  75. jpeg_write_m_byte(cinfo, 0x4F);
  76. jpeg_write_m_byte(cinfo, 0x46);
  77. jpeg_write_m_byte(cinfo, 0x49);
  78. jpeg_write_m_byte(cinfo, 0x4C);
  79. jpeg_write_m_byte(cinfo, 0x45);
  80. jpeg_write_m_byte(cinfo, 0x0);
  81. /* Add the sequencing info */
  82. jpeg_write_m_byte(cinfo, cur_marker);
  83. jpeg_write_m_byte(cinfo, (int)num_markers);
  84. /* Add the profile data */
  85. while (length--) {
  86. jpeg_write_m_byte(cinfo, *icc_data_ptr);
  87. icc_data_ptr++;
  88. }
  89. cur_marker++;
  90. }
  91. }