Programming Web Graphics with Perl and GNU Softwar

Name

Read( ) — read one or more image files

Synopsis

$image->Read(list)

The Read( ) method reads an image or an image sequence from the specified files (of any supported format) or reads in a new “blank” image with a background color. When an image is read, its file format is determined by its magic number, which is the first field in the image header. To force a specific image format, use the name of the format followed by a colon before the filename string. Filenames ending with a .gz or .Z extension (on a Unix system) will be first decompressed using uncompress or gunzip. The list can be a list of strings in any of the following forms:

$image->Read('gif:foo.gif')              # Read a single GIF file into $image
$image->Read('foo.gif', 'gumbar.jpg');   # Read two images into $image object
                                            # guessing the file format
                                            # from their magic numbers
$image->Read('*.gif');                   # Read all of the .gif files in the 
                                            # current directory into $image

open(IMAGE, "image.gif");                   # Open the file for reading
binmode IMAGE;                              # Make sure we're in binary mode
$image->Read(file=>\*IMAGE);          # Read from open Perl filehandle

Certain file formats allow more than one image to be contained in the same file (see Table 5.1). Each image in a sequence still may be accessed individually. For example, to set the transparent color of only the first image in a sequence to white, use:

$image->[0]->Transparent('#FFFFFF');

You can also read in specific “subimages” of a multi-resolution file format such as Photo CD or MPEG. Accessing subimages ...