static int
scan_JPEG_header (int verbose)
{
int marker;
/* Expect SOI at start of file */
if (first_marker() != M_SOI)
ERREXIT("Expected SOI marker first");
/* Scan miscellaneous markers until we reach SOS. */
for (;;) {
marker = next_marker();
switch (marker) {
case M_SOF0: /* Baseline */
case M_SOF1: /* Extended sequential, Huffman */
case M_SOF2: /* Progressive, Huffman */
case M_SOF3: /* Lossless, Huffman */
case M_SOF5: /* Differential sequential, Huffman */
case M_SOF6: /* Differential progressive, Huffman */
case M_SOF7: /* Differential lossless, Huffman */
case M_SOF9: /* Extended sequential, arithmetic */
case M_SOF10: /* Progressive, arithmetic */
case M_SOF11: /* Lossless, arithmetic */
case M_SOF13: /* Differential sequential, arithmetic */
case M_SOF14: /* Differential progressive, arithmetic */
case M_SOF15: /* Differential lossless, arithmetic */
if (verbose)
process_SOFn(marker);
else
skip_variable();
break;
case M_SOS: /* stop before hitting compressed data */
return marker;
case M_EOI: /* in case it's a tables-only JPEG stream */
return marker;
case M_COM:
process_COM();
break;
default: /* Anything else just gets skipped */
skip_variable(); /* we assume it has a parameter count... */
break;
}
} /* end loop */
}
static int get_jpeg_image_dimensions(ImageSize *is, int *width, int *height)
{
int marker = -1, jpeg_ok = 0;
*width = *height = -1;
if (is->infile || !is->file) {
/* Expect SOI at start of file */
if (first_marker(is) == M_SOI) {
jpeg_ok = 1;
/* Scan miscellaneous markers until we reach SOS. */
for (; marker != M_SOS && marker != M_EOI; ) {
marker = next_marker(is);
switch (marker) {
/* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,
* treated as SOFn. C4 in particular is actually DHT.
*/
case M_SOF0: /* Baseline */
case M_SOF1: /* Extended sequential, Huffman */
case M_SOF2: /* Progressive, Huffman */
case M_SOF3: /* Lossless, Huffman */
case M_SOF5: /* Differential sequential, Huffman */
case M_SOF6: /* Differential progressive, Huffman */
case M_SOF7: /* Differential lossless, Huffman */
case M_SOF9: /* Extended sequential, arithmetic */
case M_SOF10: /* Progressive, arithmetic */
case M_SOF11: /* Lossless, arithmetic */
case M_SOF13: /* Differential sequential, arithmetic */
case M_SOF14: /* Differential progressive, arithmetic */
case M_SOF15: /* Differential lossless, arithmetic */
get_image_dimensions(is, width, height);
break;
default: /* Anything else just gets skipped */
if (skip_variable(is) < 0)
return -1;
break;
}
}
}
}
return jpeg_ok;
}
static int
scan_JPEG_header (int verbose)
{
int marker;
/* Expect SOI at start of file */
if (first_marker() != M_SOI)
ERREXIT("Expected SOI marker first");
/* Scan miscellaneous markers until we reach SOS. */
for (;;) {
marker = next_marker();
switch (marker) {
/* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,
* treated as SOFn. C4 in particular is actually DHT.
*/
case M_SOF0: /* Baseline */
case M_SOF1: /* Extended sequential, Huffman */
case M_SOF2: /* Progressive, Huffman */
case M_SOF3: /* Lossless, Huffman */
case M_SOF5: /* Differential sequential, Huffman */
case M_SOF6: /* Differential progressive, Huffman */
case M_SOF7: /* Differential lossless, Huffman */
case M_SOF9: /* Extended sequential, arithmetic */
case M_SOF10: /* Progressive, arithmetic */
case M_SOF11: /* Lossless, arithmetic */
case M_SOF13: /* Differential sequential, arithmetic */
case M_SOF14: /* Differential progressive, arithmetic */
case M_SOF15: /* Differential lossless, arithmetic */
if (verbose)
process_SOFn(marker);
else
skip_variable();
break;
case M_SOS: /* stop before hitting compressed data */
return marker;
case M_EOI: /* in case it's a tables-only JPEG stream */
return marker;
case M_COM:
process_COM();
break;
case M_APP12:
/* Some digital camera makers put useful textual information into
* APP12 markers, so we print those out too when in -verbose mode.
*/
if (verbose) {
printf("APP12 contains:\n");
process_COM();
} else
skip_variable();
break;
default: /* Anything else just gets skipped */
skip_variable(); /* we assume it has a parameter count... */
break;
}
} /* end loop */
}
/** Read image info
* @param info the information structure
* @param comm (output) pointer to the comment structure (optional)
* @param file the file pointer to the image
* @return NULL on success, error message on failure
*/
const char*
readinfo (struct imageinfo* info,
struct comment** comm,
FILE* file)
{
memset (info, 0, sizeof *info);
if (read_word (file) != 0xffd8)
return "not a JPEG image file";
/* scan markers until SOS */
for (;;) {
unsigned length;
int marker = next_marker (file);
if (marker == EOF) {
eof:
return "premature end of file";
}
if ((marker & 0xf0) == 0xc0 &&
marker != 0xc4 && marker != 0xcc) {
/* start of frame marker (image dimensions) */
/** number of colour components */
int c;
length = read_word (file);
if (length < 2)
goto invalid_length;
(void) getc (file); /* skip data precision */
info->height = read_word (file);
info->width = read_word (file);
c = getc (file);
if (c == EOF)
goto eof;
if (length != (8 + ((unsigned) c) * 3))
return "inconsistent SOF marker length";
while (c--)
if (getc (file) == EOF /* component ID code */ ||
getc (file) == EOF /* sampling factors */ ||
getc (file) == EOF /* quantization table number */)
goto eof;
continue;
}
else switch (marker) {
case 0xfe:
if (!comm)
goto skip_marker;
/* comment */
length = read_word (file);
if (length < 2)
goto invalid_length;
else {
/* read the image comment */
struct comment* comment = malloc (length + sizeof *comment);
if (!comment)
return "out of memory";
length -= 2;
comment->next = 0;
if (length != fread (comment->text, 1, length, file)) {
free (comment);
goto eof;
}
comment->text[length] = 0;
/* append the comment to the list */
if (!*comm)
*comm = comment;
else {
struct comment* c;
for (c = *comm; c->next; c = c->next);
c->next = comment;
}
}
continue;
case 0xda: /* start of scan (compressed data) */
case 0xd9: /* end of image */
return 0;
}
if (feof (file))
goto eof;
skip_marker:
/* skip the rest of the marker */
length = read_word (file);
if (length < 2) {
invalid_length:
return "erroneous JPEG marker length";
}
length -= 2;
while (length--)
if (getc (file) == EOF)
goto eof;
}
}
/* analyze JPEG marker */
BOOL AnalyzeJPEG P1(imagedata *, image) {
int b, c, unit;
unsigned long i, length = 0;
#define APP_MAX 255
unsigned char appstring[APP_MAX];
BOOL SOF_done = FALSE;
/* Tommy's special trick for Macintosh JPEGs: simply skip some */
/* hundred bytes at the beginning of the file! */
do {
do { /* skip if not FF */
c = getc(image->fp);
} while (!feof(image->fp) && c != 0xFF);
do { /* skip repeated FFs */
c = getc(image->fp);
} while (c == 0xFF);
/* remember start position */
if ((image->startpos = ftell(image->fp)) < 0L) {
fprintf(stderr, "Error: internal error in ftell()!\n");
return FALSE;
}
image->startpos -= 2; /* subtract marker length */
if (c == M_SOI) {
fseek(image->fp, image->startpos, SEEK_SET);
break;
}
} while (!feof(image->fp));
if (feof(image->fp)) {
fprintf(stderr, "Error: SOI marker not found!\n");
return FALSE;
}
if (image->startpos > 0L && !quiet) {
fprintf(stderr, "Note: skipped %ld bytes ", image->startpos);
fprintf(stderr, "Probably Macintosh JPEG file?\n");
}
/* process JPEG markers */
while (!SOF_done && (c = next_marker(image->fp)) != M_EOI) {
switch (c) {
case M_ERROR:
fprintf(stderr, "Error: unexpected end of JPEG file!\n");
return FALSE;
/* The following are not officially supported in PostScript level 2 */
case M_SOF2:
case M_SOF3:
case M_SOF5:
case M_SOF6:
case M_SOF7:
case M_SOF9:
case M_SOF10:
case M_SOF11:
case M_SOF13:
case M_SOF14:
case M_SOF15:
fprintf(stderr,
"Warning: JPEG file uses compression method %X - proceeding anyway.\n",
c);
fprintf(stderr,
"PostScript output does not work on all PS interpreters!\n");
/* FALLTHROUGH */
case M_SOF0:
case M_SOF1:
length = get_2bytes(image->fp); /* read segment length */
image->bits_per_component = getc(image->fp);
image->height = get_2bytes(image->fp);
image->width = get_2bytes(image->fp);
image->components = getc(image->fp);
SOF_done = TRUE;
break;
case M_APP0: /* check for JFIF marker with resolution */
length = get_2bytes(image->fp);
for (i = 0; i < length-2; i++) { /* get contents of marker */
b = getc(image->fp);
if (i < APP_MAX) /* store marker in appstring */
appstring[i] = b;
}
/* Check for JFIF application marker and read density values
* per JFIF spec version 1.02.
* We only check X resolution, assuming X and Y resolution are equal.
* Use values only if resolution not preset by user or to be ignored.
*/
#define ASPECT_RATIO 0 /* JFIF unit byte: aspect ratio only */
#define DOTS_PER_INCH 1 /* JFIF unit byte: dots per inch */
#define DOTS_PER_CM 2 /* JFIF unit byte: dots per cm */
if (image->dpi == DPI_USE_FILE && length >= 14 &&
!strncmp((const char *)appstring, "JFIF", 4)) {
unit = appstring[7]; /* resolution unit */
/* resolution value */
image->dpi = (float) ((appstring[8]<<8) + appstring[9]);
if (image->dpi == 0.0) {
image->dpi = DPI_USE_FILE;
break;
}
switch (unit) {
/* tell the caller we didn't find a resolution value */
case ASPECT_RATIO:
image->dpi = DPI_USE_FILE;
break;
case DOTS_PER_INCH:
break;
case DOTS_PER_CM:
image->dpi *= (float) 2.54;
break;
default: /* unknown ==> ignore */
fprintf(stderr,
"Warning: JPEG file contains unknown JFIF resolution unit - ignored!\n");
image->dpi = DPI_IGNORE;
break;
}
}
break;
case M_APP14: /* check for Adobe marker */
length = get_2bytes(image->fp);
for (i = 0; i < length-2; i++) { /* get contents of marker */
b = getc(image->fp);
if (i < APP_MAX) /* store marker in appstring */
appstring[i] = b;
}
/* Check for Adobe application marker. It is known (per Adobe's TN5116)
* to contain the string "Adobe" at the start of the APP14 marker.
*/
if (length >= 12 && !strncmp((const char *) appstring, "Adobe", 5))
image->adobe = TRUE; /* set Adobe flag */
break;
case M_SOI: /* ignore markers without parameters */
case M_EOI:
case M_TEM:
case M_RST0:
case M_RST1:
case M_RST2:
case M_RST3:
case M_RST4:
case M_RST5:
case M_RST6:
case M_RST7:
break;
default: /* skip variable length markers */
length = get_2bytes(image->fp);
for (length -= 2; length > 0; length--)
(void) getc(image->fp);
break;
}
}
/* do some sanity checks with the parameters */
if (image->height <= 0 || image->width <= 0 || image->components <= 0) {
fprintf(stderr, "Error: DNL marker not supported in PostScript Level 2!\n");
return FALSE;
}
/* some broken JPEG files have this but they print anyway... */
if (length != (unsigned int) (image->components * 3 + 8))
fprintf(stderr, "Warning: SOF marker has incorrect length - ignored!\n");
if (image->bits_per_component != 8) {
fprintf(stderr, "Error: %d bits per color component ",
image->bits_per_component);
fprintf(stderr, "not supported in PostScript level 2!\n");
return FALSE;
}
if (image->components!=1 && image->components!=3 && image->components!=4) {
fprintf(stderr, "Error: unknown color space (%d components)!\n",
image->components);
return FALSE;
}
return TRUE;
}
