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cwebp/tiffdec: add TIFF metadata extraction

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currently the values of XMP/ICC are unused and EXIF is ignored.

Change-Id: I1d8b73bde4db2768f117158f986aadbaaec45804
This commit is contained in:
James Zern 2012-12-15 19:41:03 -08:00
parent df7aa07605
commit 2914ecfd56
3 changed files with 62 additions and 6 deletions
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2
examples/cwebp.c
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@ -334,7 +334,7 @@ static int ReadPicture(const char* const filename, WebPPicture* const pic,
} else if (format == JPEG_) {
ok = ReadJPEG(in_file, pic);
} else if (format == TIFF_) {
ok = ReadTIFF(filename, pic, keep_alpha);
ok = ReadTIFF(filename, pic, keep_alpha, metadata);
}
} else {
// If image size is specified, infer it as YUV format.

62
examples/tiffdec.c
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@ -19,9 +19,51 @@
#include <tiffio.h>
#include "webp/encode.h"
#include "./metadata.h"
static const struct {
ttag_t tag;
size_t storage_offset;
} kTIFFMetadataMap[] = {
{ TIFFTAG_ICCPROFILE, METADATA_OFFSET(iccp) },
{ TIFFTAG_XMLPACKET, METADATA_OFFSET(xmp) },
{ 0, 0 },
};
// Returns true on success. The caller must use MetadataFree() on 'metadata' in
// all cases.
static int ExtractMetadataFromTIFF(TIFF* const tif, Metadata* const metadata) {
int i;
uint32 exif_ifd_offset;
for (i = 0; kTIFFMetadataMap[i].tag != 0; ++i) {
MetadataPayload* const payload =
(MetadataPayload*)((uint8_t*)metadata +
kTIFFMetadataMap[i].storage_offset);
void* tag_data;
uint32 tag_data_len;
if (TIFFGetField(tif, kTIFFMetadataMap[i].tag, &tag_data_len, &tag_data) &&
!MetadataCopy((const char*)tag_data, tag_data_len, payload)) {
return 0;
}
}
// TODO(jzern): To extract the raw EXIF directory some parsing of it would be
// necessary to determine the overall size. In addition, value offsets in
// individual directory entries may need to be updated as, depending on the
// type, they are file based.
// Exif 2.2 Section 4.6.2 Tag Structure
// TIFF Revision 6.0 Part 1 Section 2 TIFF Structure #Image File Directory
if (TIFFGetField(tif, TIFFTAG_EXIFIFD, &exif_ifd_offset)) {
fprintf(stderr, "Warning: EXIF extraction from TIFF is unsupported.\n");
}
return 1;
}
int ReadTIFF(const char* const filename,
WebPPicture* const pic, int keep_alpha) {
WebPPicture* const pic, int keep_alpha,
Metadata* const metadata) {
TIFF* const tif = TIFFOpen(filename, "r");
uint32 width, height;
uint32* raster;
@ -63,8 +105,18 @@ int ReadTIFF(const char* const filename,
fprintf(stderr, "Error allocating TIFF RGBA memory!\n");
}
if (ok && keep_alpha == 2) {
WebPCleanupTransparentArea(pic);
if (ok) {
if (keep_alpha == 2) {
WebPCleanupTransparentArea(pic);
}
if (metadata != NULL) {
ok = ExtractMetadataFromTIFF(tif, metadata);
if (!ok) {
fprintf(stderr, "Error extracting TIFF metadata!\n");
MetadataFree(metadata);
WebPPictureFree(pic);
}
}
}
TIFFClose(tif);
@ -72,10 +124,12 @@ int ReadTIFF(const char* const filename,
}
#else // !WEBP_HAVE_TIFF
int ReadTIFF(const char* const filename,
struct WebPPicture* const pic, int keep_alpha) {
struct WebPPicture* const pic, int keep_alpha,
struct Metadata* const metadata) {
(void)filename;
(void)pic;
(void)keep_alpha;
(void)metadata;
fprintf(stderr, "TIFF support not compiled. Please install the libtiff "
"development package before building.\n");
return 0;

4
examples/tiffdec.h
View File

@ -14,6 +14,7 @@
extern "C" {
#endif
struct Metadata;
struct WebPPicture;
// Reads a TIFF from 'filename', returning the decoded output in 'pic'.
@ -21,7 +22,8 @@ struct WebPPicture;
// otherwise it will be RGB.
// Returns true on success.
int ReadTIFF(const char* const filename,
struct WebPPicture* const pic, int keep_alpha);
struct WebPPicture* const pic, int keep_alpha,
struct Metadata* const metadata);
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"