/*
* iccprofile.c
*
* This file provides code to read and write International Color Consortium
* (ICC) device profiles embedded in JFIF JPEG image files. The ICC has
* defined a standard format for including such data in JPEG "APP2" markers.
* The code given here does not know anything about the internal structure
* of the ICC profile data; it just knows how to put the profile data into
* a JPEG file being written, or get it back out when reading.
*
* This code depends on new features added to the IJG JPEG library as of
* IJG release 6b; it will not compile or work with older IJG versions.
*
* NOTE: this code would need surgery to work on 16-bit-int machines
* with ICC profiles exceeding 64K bytes in size. If you need to do that,
* change all the "unsigned int" variables to "INT32". You'll also need
* to find a malloc() replacement that can allocate more than 64K.
*/
#include "iccjpeg.h"
#include <stdlib.h> /* define malloc() */
/*
* Since an ICC profile can be larger than the maximum size of a JPEG marker
* (64K), we need provisions to split it into multiple markers. The format
* defined by the ICC specifies one or more APP2 markers containing the
* following data:
* Identifying string ASCII "ICC_PROFILE\0" (12 bytes)
* Marker sequence number 1 for first APP2, 2 for next, etc (1 byte)
* Number of markers Total number of APP2's used (1 byte)
* Profile data (remainder of APP2 data)
* Decoders should use the marker sequence numbers to reassemble the profile,
* rather than assuming that the APP2 markers appear in the correct sequence.
*/
#define ICC_MARKER (JPEG_APP0 + 2) /* JPEG marker code for ICC */
#define ICC_OVERHEAD_LEN 14 /* size of non-profile data in APP2 */
#define MAX_BYTES_IN_MARKER 65533 /* maximum data len of a JPEG marker */
#define MAX_DATA_BYTES_IN_MARKER (MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN)
/*
* This routine writes the given ICC profile data into a JPEG file.
* It *must* be called AFTER calling jpeg_start_compress() and BEFORE
* the first call to jpeg_write_scanlines().
* (This ordering ensures that the APP2 marker(s) will appear after the
* SOI and JFIF or Adobe markers, but before all else.)
*/
void
write_icc_profile (j_compress_ptr cinfo,
const JOCTET *icc_data_ptr,
unsigned int icc_data_len)
{
unsigned int num_markers; /* total number of markers we'll write */
int cur_marker = 1; /* per spec, counting starts at 1 */
unsigned int length; /* number of bytes to write in this marker */
/* Calculate the number of markers we'll need, rounding up of course */
num_markers = icc_data_len / MAX_DATA_BYTES_IN_MARKER;
if (num_markers * MAX_DATA_BYTES_IN_MARKER != icc_data_len)
num_markers++;
while (icc_data_len > 0) {
/* length of profile to put in this marker */
length = icc_data_len;
if (length > MAX_DATA_BYTES_IN_MARKER)
length = MAX_DATA_BYTES_IN_MARKER;
icc_data_len -= length;
/* Write the JPEG marker header (APP2 code and marker length) */
jpeg_write_m_header(cinfo, ICC_MARKER,
(unsigned int) (length + ICC_OVERHEAD_LEN));
/* Write the marker identifying string "ICC_PROFILE" (null-terminated).
* We code it in this less-than-transparent way so that the code works
* even if the local character set is not ASCII.
*/
jpeg_write_m_byte(cinfo, 0x49);
jpeg_write_m_byte(cinfo, 0x43);
jpeg_write_m_byte(cinfo, 0x43);
jpeg_write_m_byte(cinfo, 0x5F);
jpeg_write_m_byte(cinfo, 0x50);
jpeg_write_m_byte(cinfo, 0x52);
jpeg_write_m_byte(cinfo, 0x4F);
jpeg_write_m_byte(cinfo, 0x46);
jpeg_write_m_byte(cinfo, 0x49);
jpeg_write_m_byte(cinfo, 0x4C);
jpeg_write_m_byte(cinfo, 0x45);
jpeg_write_m_byte(cinfo, 0x0);
/* Add the sequencing info */
jpeg_write_m_byte(cinfo, cur_marker);
jpeg_write_m_byte(cinfo, (int) num_markers);
/* Add the profile data */
while (length--) {
jpeg_write_m_byte(cinfo, *icc_data_ptr);
icc_data_ptr++;
}
cur_marker++;
}
}
/*
* Prepare for reading an ICC profile
*/
void
setup_read_icc_profile (j_decompress_ptr cinfo)
{
/* Tell the library to keep any APP2 data it may find */
jpeg_save_markers(cinfo, ICC_MARKER, 0xFFFF);
}
/*
* Handy subroutine to test whether a saved marker is an ICC profile marker.
*/
static boolean
marker_is_icc (jpeg_saved_marker_ptr marker)
{
return
marker->marker == ICC_MARKER &&
marker->data_length >= ICC_OVERHEAD_LEN &&
/* verify the identifying string */
GETJOCTET(marker->data[0]) == 0x49 &&
GETJOCTET(marker->data[1]) == 0x43 &&
GETJOCTET(marker->data[2]) == 0x43 &&
GETJOCTET(marker->data[3]) == 0x5F &&
GETJOCTET(marker->data[4]) == 0x50 &&
GETJOCTET(marker->data[5]) == 0x52 &&
GETJOCTET(marker->data[6]) == 0x4F &&
GETJOCTET(marker->data[7]) == 0x46 &&
GETJOCTET(marker->data[8]) == 0x49 &&
GETJOCTET(marker->data[9]) == 0x4C &&
GETJOCTET(marker->data[10]) == 0x45 &&
GETJOCTET(marker->data[11]) == 0x0;
}
/*
* See if there was an ICC profile in the JPEG file being read;
* if so, reassemble and return the profile data.
*
* TRUE is returned if an ICC profile was found, FALSE if not.
* If TRUE is returned, *icc_data_ptr is set to point to the
* returned data, and *icc_data_len is set to its length.
*
* IMPORTANT: the data at **icc_data_ptr has been allocated with malloc()
* and must be freed by the caller with free() when the caller no longer
* needs it. (Alternatively, we could write this routine to use the
* IJG library's memory allocator, so that the data would be freed implicitly
* at jpeg_finish_decompress() time. But it seems likely that many apps
* will prefer to have the data stick around after decompression finishes.)
*
* NOTE: if the file contains invalid ICC APP2 markers, we just silently
* return FALSE. You might want to issue an error message instead.
*/
boolean
read_icc_profile (j_decompress_ptr cinfo,
JOCTET **icc_data_ptr,
unsigned int *icc_data_len)
{
jpeg_saved_marker_ptr marker;
int num_markers = 0;
int seq_no;
JOCTET *icc_data;
unsigned int total_length;
#define MAX_SEQ_NO 255 /* sufficient since marker numbers are bytes */
char marker_present[MAX_SEQ_NO+1]; /* 1 if marker found */
unsigned int data_length[MAX_SEQ_NO+1]; /* size of profile data in marker */
unsigned int data_offset[MAX_SEQ_NO+1]; /* offset for data in marker */
*icc_data_ptr = NULL; /* avoid confusion if FALSE return */
*icc_data_len = 0;
/* This first pass over the saved markers discovers whether there are
* any ICC markers and verifies the consistency of the marker numbering.
*/
for (seq_no = 1; seq_no <= MAX_SEQ_NO; seq_no++)
marker_present[seq_no] = 0;
for (marker = cinfo->marker_list; marker != NULL; marker = marker->next) {
if (marker_is_icc(marker)) {
if (num_markers == 0)
num_markers = GETJOCTET(marker->data[13]);
else if (num_markers != GETJOCTET(marker->data[13]))
return FALSE; /* inconsistent num_markers fields */
seq_no = GETJOCTET(marker->data[12]);
if (seq_no <= 0 || seq_no > num_markers)
return FALSE; /* bogus sequence number */
if (marker_present[seq_no])
return FALSE; /* duplicate sequence numbers */
marker_present[seq_no] = 1;
data_length[seq_no] = marker->data_length - ICC_OVERHEAD_LEN;
}
}
if (num_markers == 0)
return FALSE;
/* Check for missing markers, count total space needed,
* compute offset of each marker's part of the data.
*/
total_length = 0;
for (seq_no = 1; seq_no <= num_markers; seq_no++) {
if (marker_present[seq_no] == 0)
return FALSE; /* missing sequence number */
data_offset[seq_no] = total_length;
total_length += data_length[seq_no];
}
if (total_length == 0)
return FALSE; /* found only empty markers? */
/* Allocate space for assembled data */
icc_data = (JOCTET *) malloc(total_length * sizeof(JOCTET));
if (icc_data == NULL)
return FALSE; /* oops, out of memory */
/* and fill it in */
for (marker = cinfo->marker_list; marker != NULL; marker = marker->next) {
if (marker_is_icc(marker)) {
JOCTET FAR *src_ptr;
JOCTET *dst_ptr;
unsigned int length;
seq_no = GETJOCTET(marker->data[12]);
dst_ptr = icc_data + data_offset[seq_no];
src_ptr = marker->data + ICC_OVERHEAD_LEN;
length = data_length[seq_no];
while (length--) {
*dst_ptr++ = *src_ptr++;
}
}
}
*icc_data_ptr = icc_data;
*icc_data_len = total_length;
return TRUE;
}