Keywords: JPEG Metadata Application Segments APP0 APP1 APP2 APP3 APP12 APP13 APP14 EXIF DCF XMP RDF Photoshop IRB IPTC DCMI JFIF

# The PHP JPEG Metadata Toolkit - Documentation

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## JPEG & Intrinsic JPEG Values Function Reference

Functions for performing basic operations on a JPEG file

Function: | get_jpeg_header_data
Description: | Reads all the JPEG header segments from an JPEG image file into an array
Parameters: | filename | the filename of the file to JPEG file to read
Returns: | headerdata | Array of JPEG header segments
FALSE | if headers could not be read

Function: | put_jpeg_header_data
Description: | Writes JPEG header data into a JPEG file. Takes an array in the same format as from get_jpeg_header_data, and combines it with the image data of an existing JPEG file, to create a new JPEG file WARNING: As this function will replace all JPEG headers, including SOF etc, it is best to read the jpeg headers from a file, alter them, then put them back on the same file. If a SOF segment wer to be transfered from one file to another, the image could become unreadable unless the images were idenical size and configuration
Parameters: | old_filename | the JPEG file from which the image data will be retrieved
new_filename | the name of the new JPEG to create (can be same as old_filename)
jpeg_header_data | a JPEG header data array in the same format as from get_jpeg_header_data
Returns: | TRUE | on Success
FALSE | on Failure

Function: | get_jpeg_Comment
Description: | Retreives the contents of the JPEG Comment (COM = 0xFFFE) segment if one exists
Parameters: | jpeg_header_data | the JPEG header data, as retrieved from the get_jpeg_header_data function
Returns: | string | Contents of the Comment segement
FALSE | if the comment segment couldnt be found

Function: | Interpret_Comment_to_HTML
Description: | Generates html showing the contents of any JPEG Comment segment
Parameters: | jpeg_header_data | the JPEG header data, as retrieved from the get_jpeg_header_data function
Returns: | output | the HTML

Function: | get_jpeg_intrinsic_values
Description: | Retreives information about the intrinsic characteristics of the jpeg image, such as Bits per Component, Height and Width.
Parameters: | jpeg_header_data | the JPEG header data, as retrieved from the get_jpeg_header_data function
Returns: | array | An array containing the intrinsic JPEG values
FALSE | if the comment segment couldnt be found

Function: | Interpret_intrinsic_values_to_HTML
Description: | Generates html showing some of the intrinsic JPEG values which were retrieved with the get_jpeg_intrinsic_values function
Parameters: | values | the JPEG intrinsic values, as read from get_jpeg_intrinsic_values
Returns: | OutputStr | A string containing the HTML

Function: | get_jpeg_image_data
Description: | Retrieves the compressed image data part of the JPEG file
Parameters: | filename | the filename of the JPEG file to read
Returns: | compressed_data | A string containing the compressed data
FALSE | if retrieval failed

Function: | Generate_JPEG_APP_Segment_HTML
Description: | Generates html showing information about the Application (APP) segments which are present in the JPEG file
Parameters: | jpeg_header_data | the JPEG header data, as retrieved from the get_jpeg_header_data function
Returns: | output | A string containing the HTML