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
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.
16 #define JPEG_INTERNALS
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
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.
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)
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.)
49 jpeg_write_icc_profile(j_compress_ptr cinfo
, const JOCTET
*icc_data_ptr
,
50 unsigned int icc_data_len
)
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 */
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
);
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
)
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
;
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
));
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.
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);
94 /* Add the sequencing info */
95 jpeg_write_m_byte(cinfo
, cur_marker
);
96 jpeg_write_m_byte(cinfo
, (int)num_markers
);
98 /* Add the profile data */
100 jpeg_write_m_byte(cinfo
, *icc_data_ptr
);