1Image::Info(3) User Contributed Perl Documentation Image::Info(3)
2
6 Image::Info - Extract meta information from image files (DEPRECATED)
7
9 use Image::Info qw(image_info dim);
10 my $info = image_info("image.jpg");
12 if (my $error = $info->{error}) {
13 die "Can't parse image info: $error\n";
14 }
15 my $color = $info->{color_type};
16 my $type = image_type("image.jpg");
18 if (my $error = $type->{error}) {
19 die "Can't determine file type: $error\n";
20 }
21 die "No gif files allowed!" if $type->{file_type} eq 'GIF';
22 my($w, $h) = dim($info);
24
26 Please note that this module is deprecated and should not be used.
27 Alternatively, try one of the following modules:
28 Image::Size, Image::ExifTool.
30 The code in this module is old, unreviewed, hackish, still has numerous
32 bugs and is incomplete in quite a few cases.
33 While this module is sort-of maintained (e.g. the most critical
35 security-related bugs are fixed), no new features will be added and
36 numerous minor bugs are very likely sprinkled through the entire code
37 base. You have been warned.
38 This module provide functions to extract various kind of meta
40 information from image files.
41 EXPORTS
43 Exports nothing by default, but can export the following methods on
44 request:
45 image_info
47 image_type
48 dim
49 html_dim
50 determine_file_type
51 METHODS
53 The following functions are provided by the "Image::Info" module:
54 image_info( $file )
56 image_info( \$imgdata )
57 image_info( $file, key => value,... )
58 This function takes the name of a file or a file handle as argument
59 and will return one or more hashes (actually hash references)
60 describing the images inside the file. If there is only one image
61 in the file only one hash is returned. In scalar context, only the
62 hash for the first image is returned.
63 In case of error, and hash containing the "error" key will be
65 returned. The corresponding value will be an appropriate error
66 message.
67 If a reference to a scalar is passed as argument to this function,
69 then it is assumed that this scalar contains the raw image data
70 directly.
71 The image_info() function also take optional key/value style
73 arguments that can influence what information is returned.
74 image_type( \$imgdata )
76 Returns a hash with only one key, "file_type". The value will be
77 the type of the file. On error, sets the two keys "error" and
78 "Errno".
79 This function is a dramatically faster alternative to the
81 image_info function for situations in which you only need to find
82 the image type.
83 It uses only the internal file-type detection to do this, and thus
85 does not need to load any of the image type-specific driver
86 modules, and does not access to entire file. It also only needs
87 access to the first 11 bytes of the file.
88 To maintain some level of compatibility with image_info, image_type
90 returns in the same format, with the same error message style. That
91 is, it returns a HASH reference, with the "$type->{error}" key set
92 if there was an error.
93 On success, the HASH reference will contain the single key
95 'file_type', which represents the type of the file, expressed as
96 the type code used for the various drivers ('GIF', 'JPEG', 'TIFF'
97 and so on).
98 If there are multiple images within the file they will be ignored,
100 as this function provides only the type of the overall file, not of
101 the various images within it. This function will not return
102 multiple hashes if the file contains multiple images.
103 Of course, in all (or at least effectively all) cases the type of
105 the images inside the file is going to be the same as that of the
106 file itself.
107 dim( $info_hash )
109 Takes an hash as returned from image_info() and returns the
110 dimensions ($width, $height) of the image. In scalar context
111 returns the dimensions as a string.
112 html_dim( $info_hash )
114 Returns the dimensions as a string suitable for embedding directly
115 into HTML or SVG <img>-tags. E.g.:
116 print "<img src="..." @{[html_dim($info)]}>\n";
118 determine_file_format( $filedata )
120 Determines the file format from the passed file data (a normal Perl
121 scalar containing the first bytes of the file), and returns either
122 undef for an unknown file format, or a string describing the
123 format, like "BMP" or "JPEG".
124
126 The image_info() function returns meta information about each image in
127 the form of a reference to a hash. The hash keys used are in most
128 cases based on the TIFF element names. All lower case keys are
129 mandatory for all file formats and will always be there unless an error
130 occured (in which case the "error" key will be present.) Mixed case
131 keys will only be present when the corresponding information element is
132 available in the image.
133 The following key names are common for any image format:
135 file_media_type
137 This is the MIME type that is appropriate for the given file
138 format. The corresponding value is a string like: "image/png" or
139 "image/jpeg".
140 file_ext
142 The is the suggested file name extention for a file of the given
143 file format. The value is a 3 letter, lowercase string like "png",
144 "jpg".
145 width
147 This is the number of pixels horizontally in the image.
148 height
150 This is the number of pixels vertically in the image. (TIFF use
151 the name ImageLength for this field.)
152 color_type
154 The value is a short string describing what kind of values the
155 pixels encode. The value can be one of the following:
156 Gray
158 GrayA
159 RGB
160 RGBA
161 CMYK
162 YCbCr
163 CIELab
164 These names can also be prefixed by "Indexed-" if the image is
166 composed of indexes into a palette. Of these, only "Indexed-RGB"
167 is likely to occur.
168 It is similar to the TIFF field PhotometricInterpretation, but this
170 name was found to be too long, so we used the PNG inpired term
171 instead.
172 resolution
174 The value of this field normally gives the physical size of the
175 image on screen or paper. When the unit specifier is missing then
176 this field denotes the squareness of pixels in the image.
177 The syntax of this field is:
179 <res> <unit>
181 <xres> "/" <yres> <unit>
182 <xres> "/" <yres>
183 The <res>, <xres> and <yres> fields are numbers. The <unit> is a
185 string like "dpi", "dpm" or "dpcm" (denoting "dots per
186 inch/cm/meter).
187 SamplesPerPixel
189 This says how many channels there are in the image. For some image
190 formats this number might be higher than the number implied from
191 the "color_type".
192 BitsPerSample
194 This says how many bits are used to encode each of samples. The
195 value is a reference to an array containing numbers. The number of
196 elements in the array should be the same as "SamplesPerPixel".
197 Comment
199 Textual comments found in the file. The value is a reference to an
200 array if there are multiple comments found.
201 Interlace
203 If the image is interlaced, then this tell which interlace method
204 is used.
205 Compression
207 This tells you which compression algorithm is used.
208 Gamma
210 A number.
211 LastModificationTime
213 A ISO date string
214
216 The following image file formats are supported:
217 BMP This module supports the Microsoft Device Independent Bitmap format
219 (BMP, DIB, RLE).
220 For more information see Image::Info::BMP.
222 GIF Both GIF87a and GIF89a are supported and the version number is
224 found as "GIF_Version" for the first image. GIF files can contain
225 multiple images, and information for all images will be returned if
226 image_info() is called in list context. The Netscape-2.0 extention
227 to loop animation sequences is represented by the "GIF_Loop" key
228 for the first image. The value is either "forever" or a number
229 indicating loop count.
230 JPEG
232 For JPEG files we extract information both from "JFIF" and "Exif"
233 application chunks.
234 "Exif" is the file format written by most digital cameras. This
236 encode things like timestamp, camera model, focal length, exposure
237 time, aperture, flash usage, GPS position, etc. The following web
238 page contain description of the fields that can be present:
239 http://www.ba.wakwak.com/~tsuruzoh/Computer/Digicams/exif-e.html
241 The "Exif" spec can be found at:
243 http://www.exif.org/specifications.html
245 PNG Information from IHDR, PLTE, gAMA, pHYs, tEXt, tIME chunks are
247 extracted. The sequence of chunks are also given by the
248 "PNG_Chunks" key.
249 PBM/PGM/PPM
251 All information available is extracted.
252 SVG Provides a plethora of attributes and metadata of an SVG vector
254 grafic.
255 TIFF
257 The "TIFF" spec can be found at:
258 <http://partners.adobe.com/public/developer/tiff/>
259 The EXIF spec can be found at: <http://www.exif.org/>
261 XBM See Image::Info::XBM for details.
263 XPM See Image::Info::XPM for details.
265
267 Note that while the module is still maintained, no new features will be
268 added and numerous bugs remain throughout the code base.
269 Especially the EXIF parsing code is buggy, not tested at all, and quite
271 incomplete (a lot of manufacturer's MakerNotes and tags are not parsed
272 at all). If you want a stable, feature-complete, up-to-date and tested
273 EXIF parsing library, please use Image::ExifTool.
274 Likewise, the image parsing code is quite hackish and seems to contain
276 an endless supply of bugs that crash, or hang with malformed input.
277
279 Image::Size, Image::ExifTool
280
282 Copyright 1999-2004 Gisle Aas.
283 See the CREDITS file for a list of contributors and authors.
285 Now maintained by Tels - (c) 2006 - 2008.
287
289 This library is free software; you can redistribute it and/or modify it
290 under the same terms as Perl v5.8.8 itself.
291perl v5.12.0 2008-03-30 Image::Info(3)