jpeg

jpeg

Functions

Description

Functions

iptc_jpeg_read_ps3 ()

int
iptc_jpeg_read_ps3 (FILE *infile,
                    unsigned char *buf,
                    unsigned int size);

Scans the headers of a JPEG file looking for a "Photoshop 3.0" header, and if found, stores the raw contents of this header in the buf buffer. The Photoshop 3.0 header is a series of records found in the APP13 section of a JPEG file. If a JPEG file contains IPTC metadata, the metadata is stored in one of the Photoshop 3.0 records.

Parameters

infile

an open JPEG file with the current position set to the start of the file

 

buf

an output buffer to store the Photoshop 3.0 data

 

size

the size of the output buffer

 

Returns

the number of bytes stored on success, 0 if the PS3 header was not found, or -1 if an error occurred.


iptc_jpeg_ps3_find_iptc ()

int
iptc_jpeg_ps3_find_iptc (const unsigned char *ps3,
                         unsigned int ps3_size,
                         unsigned int *iptc_len);

Parses a "Photoshop 3.0" header in search of IPTC metadata.

Parameters

ps3

the data of a Photoshop 3.0 header to search

 

ps3_size

size in bytes of ps3

 

iptc_len

output parameter, the size in bytes of any found IPTC data

 

Returns

the offset in bytes from the start of ps3 where a block of IPTC metadata begins, 0 if no IPTC metadata was found, -1 on error.


iptc_jpeg_ps3_save_iptc ()

int
iptc_jpeg_ps3_save_iptc (const unsigned char *ps3,
                         unsigned int ps3_size,
                         const unsigned char *iptc,
                         unsigned int iptc_size,
                         unsigned char *buf,
                         unsigned int size);

Takes a Photoshop 3.0 header, ps3 , removes any existing IPTC data inside that header, and inserts the new IPTC data from iptc . Any other non-IPTC portions of ps3 are left unmodified. If ps3 is NULL, a blank PS3 header is created. If iptc is NULL, the output PS3 header will contain no IPTC data, even if ps3 originally contained some.

Parameters

ps3

a template PS3 header in which to insert the new iptc data. Any non-IPTC data in this template will be preserved in the output Photoshop 3.0 header. If NULL, a PS3 header will be generated from scratch.

 

ps3_size

size in bytes of ps3

 

iptc

the IPTC bytestream to be encapsulated in the PS3 output. The IPTC bytestream can be generated with iptc_data_save(). If NULL, the output will still be a valid PS3 header, but without any contained IPTC data.

 

iptc_size

size in bytes of iptc

 

buf

output buffer for the generated PS3 header

 

size

size in bytes of buf

 

Returns

the number of bytes written to buf ; -1 on error.


iptc_jpeg_save_with_ps3 ()

int
iptc_jpeg_save_with_ps3 (FILE *infile,
                         FILE *outfile,
                         const unsigned char *ps3,
                         unsigned int ps3_size);

Takes an existing JPEG file, infile , removes any existing Photoshop 3.0 header from it, and adds a new PS3 header, writing the output to outfile . infile must be open for reading and is expected to point to the beginning of the JPEG file, which should be different from outfile , which must be open for writing. If ps3 is NULL, the output will contain no PS3 header. PS3 headers reside in the APP13 section of the JPEG file, which is created if necessary. All other headers and data will be copied directly from infile without modification.

Parameters

infile

the file stream from which the image data is copied

 

outfile

the output file stream

 

ps3

the Photoshop 3.0 header to add to the output file

 

ps3_size

size in bytes of ps3

 

Returns

0 on success, -1 on error. Note that even in error, some data may have been written to outfile , and its contents should be considered undefined.

Types and Values