Image::Info - Extract meta information from image files |
Image::Info - Extract meta information from image files
use Image::Info qw(image_info dim);
my $info = image_info("image.jpg"); if (my $error = $info->{error}) { die "Can't parse image info: $error\n"; } my $color = $info->{color_type}; my $type = image_type("image.jpg"); if (my $error = $type->{error}) { die "Can't determine file type: $error\n"; } die "No gif files allowed!" if $type->{file_type} eq 'GIF'; my($w, $h) = dim($info);
This module provide functions to extract various kinds of meta information from image files.
Exports nothing by default, but can export the following methods on request:
image_info image_type dim html_dim determine_file_type
The following functions are provided by the Image::Info
module:
In case of error, a hash containing the ``error'' key will be returned. The corresponding value will be an appropriate error message.
If a reference to a scalar is passed as an argument to this function, then it is assumed that this scalar contains the raw image data directly.
The image_info()
function also take optional key/value style arguments
that can influence what information is returned.
file_type
. The value
will be the type of the file. On error, sets the two keys
error
and Errno
.
This function is a dramatically faster alternative to the image_info function for situations in which you only need to find the image type.
It uses only the internal file-type detection to do this, and thus does not need to load any of the image type-specific driver modules, and does not access to entire file. It also only needs access to the first 11 bytes of the file.
To maintain some level of compatibility with image_info, image_type
returns in the same format, with the same error message style. That is,
it returns a HASH reference, with the $type->{error}
key set if
there was an error.
On success, the HASH reference will contain the single key file_type
,
which represents the type of the file, expressed as the type code used for
the various drivers ('GIF', 'JPEG', 'TIFF' and so on).
If there are multiple images within the file they will be ignored, as this function provides only the type of the overall file, not of the various images within it. This function will not return multiple hashes if the file contains multiple images.
Of course, in all (or at least effectively all) cases the type of the images inside the file is going to be the same as that of the file itself.
image_info()
and returns the dimensions
($width, $height) of the image. In scalar context returns the
dimensions as a string.
print "<img src="..." @{[html_dim($info)]}>\n";
The image_info()
function returns meta information about each image in
the form of a reference to a hash. The hash keys used are in most
cases based on the TIFF element names. All lower case keys are
mandatory for all file formats and will always be there unless an
error occured (in which case the ``error'' key will be present.) Mixed
case keys will only be present when the corresponding information
element is available in the image.
The following key names are common for any image format:
Gray GrayA RGB RGBA CMYK YCbCr CIELab
These names can also be prefixed by ``Indexed-'' if the image is composed of indexes into a palette. Of these, only ``Indexed-RGB'' is likely to occur.
It is similar to the TIFF field ``PhotometricInterpretation'', but this name was found to be too long, so we used the PNG inpired term instead.
The syntax of this field is:
<res> <unit> <xres> "/" <yres> <unit> <xres> "/" <yres>
The <res>, <xres> and <yres> fields are numbers. The <unit> is a
string like dpi
, dpm
or dpcm
(denoting ``dots per
inch/cm/meter).
color_type
.
SamplesPerPixel
.
The following image file formats are supported:
For more information see the Image::Info::BMP manpage.
GIF_Version
for the first image. GIF files can contain multiple
images, and information for all images will be returned if
image_info()
is called in list context. The Netscape-2.0 extension to
loop animation sequences is represented by the GIF_Loop
key for the
first image. The value is either ``forever'' or a number indicating
loop count.
JFIF
and Exif
application chunks.
Exif
is the file format written by most digital cameras. This
encode things like timestamp, camera model, focal length, exposure
time, aperture, flash usage, GPS position, etc.
The Exif
spec can be found at:
http://www.exif.org/specifications.html.
The color_type
element may have the following values: Gray
,
YCbCr
, and CMYK
. Note that detecting RGB
and YCCK
currently does not work, but will hopefully in future.
PNG_Chunks
key.
TIFF
spec can be found at:
http://partners.adobe.com/public/developer/tiff/
The EXIF spec can be found at: http://www.exif.org/specifications.html
While this module is fine for parsing basic image information like image type, dimensions and color depth, it is probably not good enough for parsing out more advanced information like EXIF data. If you want an up-to-date and tested EXIF parsing library, please use the Image::ExifTool manpage.
the Image::Size manpage, the Image::ExifTool manpage
Copyright 1999-2004 Gisle Aas.
See the CREDITS file for a list of contributors and authors.
Tels - (c) 2006 - 2008.
Current maintainer: Slaven Rezic - (c) 2008 - 2015.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl v5.8.8 itself.
Image::Info - Extract meta information from image files |