=head1 SYNOPSIS
+ use Imager;
my $img = ...;
$img->write(file=>$filename, type=>$type)
or die "Cannot write: ",$img->errstr;
+ # type is optional if we can guess the format from the filename
+ $img->write(file => "foo.png")
+ or die "Cannot write: ",$img->errstr;
+
$img = Imager->new;
$img->read(file=>$filename, type=>$type)
or die "Cannot read: ", $img->errstr;
+ # type is optional if we can guess the type from the file data
+ # and we normally can guess
+ $img->read(file => $filename)
+ or die "Cannot read: ", $img->errstr;
+
Imager->write_multi({ file=> $filename, ... }, @images)
or die "Cannot write: ", Imager->errstr;
Imager->set_file_limits(width=>$max_width, height=>$max_height)
+ my @read_types = Imager->read_types;
+ my @write_types = Imager->write_types;
+
+ # we can write/write_multi to things other than filenames
+ my $data;
+ $img->write(data => \$data, type => $type) or die;
+
+ my $fh = ... ; # eg. IO::File
+ $img->write(fh => $fh, type => $type) or die;
+
+ $img->write(fd => fileno($fh), type => $type) or die;
+
+ # some file types need seek callbacks too
+ $img->write(callback => \&write_callback, type => $type) or die;
+
+ # and similarly for read/read_multi
+ $img->read(data => $data) or die;
+ $img->read(fh => $fh) or die;
+ $img->read(fd => fileno($fh)) or die;
+ $img->read(callback => \&read_callback) or die;
+
+ use Imager 0.68;
+ my $img = Imager->new(file => $filename)
+ or die Imager->errstr;
+
=head1 DESCRIPTION
You can read and write a variety of images formats, assuming you have
print join " ", keys %Imager::formats;
This will include some other information identifying libraries rather
-than file formats.
+than file formats. For new code you might find the L</read_types()>
+or L</write_types()> methods useful.
=over
$img->read(file=>$filename, type=>$type)
or die "Cannot read $filename: ", $img->errstr;
+In most cases Imager can auto-detect the file type, so you can just
+supply the file name:
+
+ $img->read(file => $filename)
+ or die "Cannot read $filename: ", $img->errstr;
+
+The read() method accepts the C<allow_partial> parameter. If this is
+non-zero then read() can return true on an incomplete image and set
+the C<i_incomplete> tag.
+
+From Imager 0.68 you can supply most read() parameters to the new()
+method to read the image file on creation. If the read fails, check
+Imager->errstr() for the cause:
+
+ use Imager 0.68;
+ my $img = Imager->new(file => $filename)
+ or die "Cannot read $filename: ", Imager->errstr;
+
=item write
and the C<write()> method to write an image:
my @imgs = Imager->read_multi(file=>$filename, type=>$type)
or die "Cannot read $filename: ", Imager->errstr;
+As with the read() method, Imager will normally detect the C<type>
+automatically.
+
=item write_multi
and if you want to write multiple images to a single file use the
Imager->write_multi({ file=> $filename, type=>$type }, @images)
or die "Cannot write $filename: ", Imager->errstr;
+=item read_types()
+
+This is a class method that returns a list of the image file types
+that Imager can read.
+
+ my @types = Imager->read_types;
+
+These types are the possible values for the C<type> parameter, not
+necessarily the extension of the files you're reading.
+
+It is possible for extra file read handlers to be loaded when
+attempting to read a file, which may modify the list of available read
+types.
+
+=item write_types()
+
+This is a class method that returns a list of the image file types
+that Imager can write.
+
+ my @types = Imager->write_types;
+
+Note that these are the possible values for the C<type> parameter, not
+necessarily the extension of the files you're writing.
+
+It is possible for extra file write handlers to be loaded when
+attempting to write a file, which may modify the list of available
+write types.
+
=back
-If the I<filename> includes an extension that Imager recognizes, then
-you don't need the I<type>, but you may want to provide one anyway.
-See L</Guessing types> for information on controlling this
-recognition.
+When writing, if the C<filename> includes an extension that Imager
+recognizes, then you don't need the C<type>, but you may want to
+provide one anyway. See L</Guessing types> for information on
+controlling this recognition.
The C<type> parameter is a lowercase representation of the file type,
and can be any of the following:
png Portable Network Graphics (PNG)
pnm Portable aNyMap (PNM)
raw Raw
- rgb SGI .rgb files
+ sgi SGI .rgb files
tga TARGA
tiff Tagged Image File Format (TIFF)
=over
-=item file
+=item *
+
+C<file> - The C<file> parameter is the name of the image file to be
+written to or read from. If Imager recognizes the extension of the
+file you do not need to supply a C<type>.
-The C<file> parameter is the name of the image file to be written to
-or read from. If Imager recognizes the extension of the file you do
-not need to supply a C<type>.
+ # write in tiff format
+ $image->write(file => "example.tif")
+ or die $image->errstr;
-=item fh
+ $image->write(file => 'foo.tmp', type => 'tiff')
+ or die $image->errstr;
-C<fh> is a file handle, typically either returned from
+ my $image = Imager->new;
+ $image->read(file => 'example.tif')
+ or die $image->errstr;
+
+=item *
+
+C<fh> - C<fh> is a file handle, typically either returned from
C<<IO::File->new()>>, or a glob from an C<open> call. You should call
C<binmode> on the handle before passing it to Imager.
is flushed , since Imager will write to the file descriptor (from
fileno()) rather than writing at the perl level.
-=item fd
+ $image->write(fh => \*STDOUT, type => 'gif')
+ or die $image->errstr;
+
+ # for example, a file uploaded via CGI.pm
+ $image->read(fd => $cgi->param('file'))
+ or die $image->errstr;
+
+=item *
-C<fd> is a file descriptor. You can get this by calling the
+C<fd> - C<fd> is a file descriptor. You can get this by calling the
C<fileno()> function on a file handle, or by using one of the standard
file descriptor numbers.
buffered output, otherwise it may appear in the output stream after
the image.
-=item data
+ $image->write(fd => file(STDOUT), type => 'gif')
+ or die $image->errstr;
-When reading data, C<data> is a scalar containing the image file data,
-when writing, C<data> is a reference to the scalar to save the image
-file data too. For GIF images you will need giflib 4 or higher, and
-you may need to patch giflib to use this option for writing.
+=item *
+
+C<data> - When reading data, C<data> is a scalar containing the image
+file data, when writing, C<data> is a reference to the scalar to save
+the image file data too. For GIF images you will need C<giflib> 4 or
+higher, and you may need to patch C<giflib> to use this option for
+writing.
+
+ my $data;
+ $image->write(data => \$data, type => 'tiff')
+ or die $image->errstr;
+
+ my $data = $row->{someblob}; # eg. from a database
+ my @images = Imager->read_multi(data => $data)
+ or die Imager->errstr;
-=item callback
+=item *
-Imager will make calls back to your supplied coderefs to read, write
-and seek from/to/through the image file.
+C<callback> - Imager will make calls back to your supplied coderefs to
+read, write and seek from/to/through the image file.
When reading from a file you can use either C<callback> or C<readcb>
to supply the read callback, and when writing C<callback> or
when there is no more data to be written. This could be used to flush
buffered data.
+ # contrived
+ my $data;
+ sub mywrite {
+ $data .= unpack("H*", shift);
+ 1;
+ }
+ Imager->write_multi({ callback => \&mywrite, type => 'gif'}, @images)
+ or die Imager->errstr;
+
+Note that for reading you'll almost always need to provide a
+C<seekcb>.
+
=back
=head2 Guessing types
-Imager uses the code reference in $Imager::FORMATGUESS to guess the
-file type when you don't supply a C<type>. The code reference is
-called with a single parameter, the filename of the file. The code
-reference is only called if a C<file> parameter is supplied to the
-file access method.
+When writing to a file, if you don't supply a C<type> parameter Imager
+will attempt to guess it from the file name. This is done by calling
+the code reference stored in C<$Imager::FORMATGUESS>. This is only
+done when write() or write_multi() is called with a C<file> parameter.
+
+The default function value of C<$Imager::FORMATGUESS> is
+C<\&Imager::def_guess_type>.
+
+=over
+
+=item def_guess_type()
-Return either a valid Imager file type, or undef.
+This is the default function Imager uses to derive a file type from a
+file name. This is a function, not a method.
+
+Accepts a single parameter, the file name and returns the type or
+undef.
+
+=back
+
+You can replace function with your own implementation if you have some
+specialized need. The function takes a single parameter, the name of
+the file, and should return either a file type or under.
# I'm writing jpegs to weird filenames
local $Imager::FORMATGUESS = sub { 'jpeg' };
+When reading a file Imager examines beginning of the file for
+identifying information. The current implementation attempts to
+detect the following image types beyond those supported by Imager:
+
+=for stopwords Photoshop
+
+=over
+
+C<xpm>, C<mng>, C<jng>, C<ilbm>, C<pcx>, C<fits>, C<psd> (Photoshop), C<eps>, Utah
+C<RLE>.
+
+=back
+
=head2 Limiting the sizes of images you read
=over
At some point in the future these obsolete options will no longer be
supported.
+=for stopwords aNy PixMaps BitMap
+
=head2 PNM (Portable aNy Map)
-Imager can write PGM (Portable Gray Map) and PPM (Portable PixMaps)
-files, depending on the number of channels in the image. Currently
-the images are written in binary formats. Only 1 and 3 channel images
-can be written, including 1 and 3 channel paletted images.
+Imager can write C<PGM> (Portable Gray Map) and C<PPM> (Portable
+PixMaps) files, depending on the number of channels in the image.
+Currently the images are written in binary formats. Only 1 and 3
+channel images can be written, including 1 and 3 channel paletted
+images.
$img->write(file=>'foo.ppm') or die $img->errstr;
-Imager can read both the ASCII and binary versions of each of the PBM
-(Portable BitMap), PGM and PPM formats.
+Imager can read both the ASCII and binary versions of each of the
+C<PBM> (Portable BitMap), C<PGM> and C<PPM> formats.
$img->read(file=>'foo.ppm') or die $img->errstr;
PNM does not support the spatial resolution tags.
+The following tags are set when reading a PNM file:
+
+=over
+
+=item *
+
+X<pnm_maxval>C<pnm_maxval> - the C<maxvals> number from the PGM/PPM header.
+Always set to 2 for a C<PBM> file.
+
+=item *
+
+X<pnm_type>C<pnm_type> - the type number from the C<PNM> header, 1 for ASCII
+C<PBM> files, 2 for ASCII C<PGM> files, 3 for ASCII c<PPM> files, 4 for binary
+C<PBM> files, 5 for binary C<PGM> files, 6 for binary C<PPM> files.
+
+=back
+
+The following tag is checked when writing an image with more than
+8-bits/sample:
+
+=over
+
+=item *
+
+X<pnm_write_wide_data>pnm_write_wide_data - if this is non-zero then
+write() can write C<PGM>/C<PPM> files with 16-bits/sample. Some
+applications, for example GIMP 2.2, and tools can only read
+8-bit/sample binary PNM files, so Imager will only write a 16-bit
+image when this tag is non-zero.
+
+=back
+
=head2 JPEG
+=for stopwords composited
+
You can supply a C<jpegquality> parameter (0-100) when writing a JPEG
-file, which defaults to 75%. Only 1 and 3 channel images
-can be written, including 1 and 3 channel paletted images.
+file, which defaults to 75%. If you write an image with an alpha
+channel to a JPEG file then it will be composited against the
+background set by the C<i_background> parameter (or tag).
$img->write(file=>'foo.jpg', jpegquality=>90) or die $img->errstr;
-Imager will read a grayscale JPEG as a 1 channel image and a color
+Imager will read a gray scale JPEG as a 1 channel image and a color
JPEG as a 3 channel image.
$img->read(file=>'foo.jpg') or die $img->errstr;
=over
-=item jpeg_density_unit
+=item *
-The value of the density unit field in the JFIF header. This is
-ignored on writing if the i_aspect_only tag is non-zero.
+C<jpeg_density_unit> - The value of the density unit field in the
+C<JFIF> header. This is ignored on writing if the C<i_aspect_only>
+tag is non-zero.
The C<i_xres> and C<i_yres> tags are expressed in pixels per inch no
matter the value of this tag, they will be converted to/from the value
stored in the JPEG file.
-=item jpeg_density_unit_name
+=item *
-This is set when reading a JPEG file to the name of the unit given by
-C<jpeg_density_unit>. Possible results include C<inch>,
-C<centimeter>, C<none> (the C<i_aspect_only> tag is also set reading
-these files). If the value of jpeg_density_unit is unknown then this
-tag isn't set.
+C<jpeg_density_unit_name> - This is set when reading a JPEG file to
+the name of the unit given by C<jpeg_density_unit>. Possible results
+include C<inch>, C<centimeter>, C<none> (the C<i_aspect_only> tag is
+also set reading these files). If the value of C<jpeg_density_unit>
+is unknown then this tag isn't set.
-=item jpeg_comment
+=item *
-Text comment.
+C<jpeg_comment> - Text comment.
+
+=item *
+
+C<jpeg_progressive> - Whether the JPEG file is a progressive
+file. (Imager 0.84)
=back
JPEG supports the spatial resolution tags C<i_xres>, C<i_yres> and
C<i_aspect_only>.
-If an APP1 block containing EXIF information is found, then any of the
-following tags can be set:
+=for stopwords EXIF
+
+If an C<APP1> block containing EXIF information is found, then any of the
+following tags can be set when reading a JPEG image:
=over
=back
-The following derived tags can also be set:
+The following derived tags can also be set when reading a JPEG image:
=over
example if C<exf_metering_mode> is C<5> then
C<exif_metering_mode_name> is set to C<Pattern>.
-=head2 GIF (Graphics Interchange Format)
+eg.
+
+ my $image = Imager->new;
+ $image->read(file => 'exiftest.jpg')
+ or die "Cannot load image: ", $image->errstr;
+ print $image->tags(name => "exif_image_description"), "\n";
+ print $image->tags(name => "exif_exposure_mode"), "\n";
+ print $image->tags(name => "exif_exposure_mode_name"), "\n";
+
+ # for the exiftest.jpg in the Imager distribution the output would be:
+ Imager Development Notes
+ 0
+ Auto exposure
+
+Imager will not write EXIF tags to any type of image, if you need more
+advanced EXIF handling, consider L<Image::ExifTool>.
+
+=for stopwords IPTC
+
+=over
+
+=item parseiptc()
+
+Historically, Imager saves IPTC data when reading a JPEG image, the
+parseiptc() method returns a list of key/value pairs resulting from a
+simple decoding of that data.
+
+Any future IPTC data decoding is likely to go into tags.
+
+=back
+
+=head2 GIF
When writing one of more GIF images you can use the same
L<Quantization Options|Imager::ImageTypes> as you can when converting
=over
-=item gif_left
+=item *
-the offset of the image from the left of the "screen" ("Image Left
-Position")
+gif_left - the offset of the image from the left of the "screen"
+("Image Left Position")
-=item gif_top
+=item *
-the offset of the image from the top of the "screen" ("Image Top Position")
+gif_top - the offset of the image from the top of the "screen" ("Image
+Top Position")
-=item gif_interlace
+=item *
-non-zero if the image was interlaced ("Interlace Flag")
+gif_interlace - non-zero if the image was interlaced ("Interlace
+Flag")
-=item gif_screen_width
+=item *
-=item gif_screen_height
+gif_screen_width, gif_screen_height - the size of the logical
+screen. When writing this is used as the minimum. If any image being
+written would extend beyond this then the screen size is extended.
+("Logical Screen Width", "Logical Screen Height").
-the size of the logical screen. When writing this is used as the
-minimum. If any image being written would extend beyond this the
-screen size is extended. ("Logical Screen Width", "Logical Screen
-Height").
+=item *
-When writing this is used as a minimum, if the combination of the
-image size and the image's C<gif_left> and C<gif_top> is beyond this
-size then the screen size will be expanded.
+gif_local_map - Non-zero if this image had a local color map. If set
+for an image when writing the image is quantized separately from the
+other images in the file.
-=item gif_local_map
+=item *
-Non-zero if this image had a local color map. If set for an image
-when writing the image is quantized separately from the other images
-in the file.
+gif_background - The index in the global color map of the logical
+screen's background color. This is only set if the current image uses
+the global color map. You can set this on write too, but for it to
+choose the color you want, you will need to supply only paletted
+images and set the C<gif_eliminate_unused> tag to 0.
-=item gif_background
+=item *
-The index in the global colormap of the logical screen's background
-color. This is only set if the current image uses the global
-colormap. You can set this on write too, but for it to choose the
-color you want, you will need to supply only paletted images and set
-the C<gif_eliminate_unused> tag to 0.
+gif_trans_index - The index of the color in the color map used for
+transparency. If the image has a transparency then it is returned as
+a 4 channel image with the alpha set to zero in this palette entry.
+This value is not used when writing. ("Transparent Color Index")
-=item gif_trans_index
+=item *
-The index of the color in the colormap used for transparency. If the
-image has a transparency then it is returned as a 4 channel image with
-the alpha set to zero in this palette entry. This value is not used
-when writing. ("Transparent Color Index")
+gif_trans_color - A reference to an Imager::Color object, which is the
+color to use for the palette entry used to represent transparency in
+the palette. You need to set the C<transp> option (see
+L<Imager::ImageTypes/"Quantization options">) for this value to be
+used.
-=item gif_trans_color
+=item *
-A reference to an Imager::Color object, which is the colour to use for
-the palette entry used to represent transparency in the palette. You
-need to set the transp option (see L<Quantization options>) for this
-value to be used.
+gif_delay - The delay until the next frame is displayed, in 1/100 of a
+second. ("Delay Time").
-=item gif_delay
+=item *
-The delay until the next frame is displayed, in 1/100 of a second.
-("Delay Time").
+gif_user_input - whether or not a user input is expected before
+continuing (view dependent) ("User Input Flag").
-=item gif_user_input
+=item *
-whether or not a user input is expected before continuing (view dependent)
-("User Input Flag").
+gif_disposal - how the next frame is displayed ("Disposal Method")
-=item gif_disposal
+=item *
-how the next frame is displayed ("Disposal Method")
+gif_loop - the number of loops from the Netscape Loop extension. This
+may be zero to loop forever.
-=item gif_loop
+=item *
-the number of loops from the Netscape Loop extension. This may be zero.
+gif_comment - the first block of the first GIF comment before each
+image.
-=item gif_comment
+=item *
-the first block of the first gif comment before each image.
+gif_eliminate_unused - If this is true, when you write a paletted
+image any unused colors will be eliminated from its palette. This is
+set by default.
-=item gif_eliminate_unused
+=item *
-If this is true, when you write a paletted image any unused colors
-will be eliminated from its palette. This is set by default.
+gif_colormap_size - the original size of the color map for the image.
+The color map of the image may have been expanded to include out of
+range color indexes.
=back
-Where applicable, the ("name") is the name of that field from the GIF89
+Where applicable, the ("name") is the name of that field from the C<GIF89>
standard.
-The following gif writing options are obsolete, you should set the
+The following GIF writing options are obsolete, you should set the
corresponding tag in the image, either by using the tags functions, or
by supplying the tag and value as options.
=over
-=item gif_each_palette
+=item *
-Each image in the gif file has it's own palette if this is non-zero.
-All but the first image has a local colour table (the first uses the
-global colour table.
+gif_each_palette - Each image in the GIF file has it's own palette if
+this is non-zero. All but the first image has a local color table
+(the first uses the global color table.
Use C<gif_local_map> in new code.
-=item interlace
+=item *
-The images are written interlaced if this is non-zero.
+interlace - The images are written interlaced if this is non-zero.
Use C<gif_interlace> in new code.
-=item gif_delays
+=item *
-A reference to an array containing the delays between images, in 1/100
-seconds.
+gif_delays - A reference to an array containing the delays between
+images, in 1/100 seconds.
Use C<gif_delay> in new code.
-=item gif_positions
+=item *
-A reference to an array of references to arrays which represent screen
-positions for each image.
+gif_positions - A reference to an array of references to arrays which
+represent screen positions for each image.
New code should use the C<gif_left> and C<gif_top> tags.
-=item gif_loop_count
+=item *
-If this is non-zero the Netscape loop extension block is generated,
-which makes the animation of the images repeat.
+gif_loop_count - If this is non-zero the Netscape loop extension block
+is generated, which makes the animation of the images repeat.
-This is currently unimplemented due to some limitations in giflib.
+This is currently unimplemented due to some limitations in C<giflib>.
=back
$image->read(file=>"example.gif", page=>1)
or die "Cannot read second page: ",$image->errstr,"\n";
-Before release 0.46, Imager would read multi-image GIF image files
+Before release 0.46, Imager would read multiple image GIF image files
into a single image, overlaying each of the images onto the virtual
GIF screen.
As of 0.46 the default is to read the first image from the file, as if
called with C<< page => 0 >>.
-You can return to the previous behaviour by calling read with the
+You can return to the previous behavior by calling read with the
C<gif_consolidate> parameter set to a true value:
$img->read(file=>$some_gif_file, gif_consolidate=>1);
+As with the to_paletted() method, if you supply a colors parameter as
+a reference to an array, this will be filled with Imager::Color
+objects of the color table generated for the image file.
+
=head2 TIFF (Tagged Image File Format)
Imager can write images to either paletted or RGB TIFF images,
-depending on the type of the source image. Currently if you write a
-16-bit/sample or double/sample image it will be written as an
-8-bit/sample image. Only 1 or 3 channel images can be written.
+depending on the type of the source image.
+
+When writing direct color images to TIFF the sample size of the
+output file depends on the input:
+
+=over
+
+=item *
+
+double/sample - written as 32-bit/sample TIFF
+
+=item *
+
+16-bit/sample - written as 16-bit/sample TIFF
+
+=item *
+
+8-bit/sample - written as 8-bit/sample TIFF
+
+=back
+
+For paletted images:
+
+=over
+
+=item *
+
+C<< $img->is_bilevel >> is true - the image is written as bi-level
+
+=item *
+
+otherwise - image is written as paletted.
+
+=back
If you are creating images for faxing you can set the I<class>
parameter set to C<fax>. By default the image is written in fine
mode, but this can be overridden by setting the I<fax_fine> parameter
to zero. Since a fax image is bi-level, Imager uses a threshold to
decide if a given pixel is black or white, based on a single channel.
-For greyscale images channel 0 is used, for color images channel 1
+For gray scale images channel 0 is used, for color images channel 1
(green) is used. If you want more control over the conversion you can
use $img->to_paletted() to product a bi-level image. This way you can
use dithering:
- my $bilevel = $img->to_paletted(colors=>[ NC(0,0,0), NC(255,255,255) ],
- make_colors => 'none',
+ my $bilevel = $img->to_paletted(make_colors => 'mono',
translate => 'errdiff',
errdiff => 'stucki');
=over
-=item class
+=item *
-If set to 'fax' the image will be written as a bi-level fax image.
+C<class> - If set to 'fax' the image will be written as a bi-level fax
+image.
-=item fax_fine
+=item *
-By default when I<class> is set to 'fax' the image is written in fine
-mode, you can select normal mode by setting I<fax_fine> to 0.
+C<fax_fine> - By default when C<class> is set to 'fax' the image is
+written in fine mode, you can select normal mode by setting
+C<fax_fine> to 0.
=back
Imager should be able to read any TIFF image you supply. Paletted
TIFF images are read as paletted Imager images, since paletted TIFF
images have 16-bits/sample (48-bits/color) this means the bottom
-8-bits are lost, but this shouldn't be a big deal. Currently all
-direct color images are read at 8-bits/sample.
+8-bits are lost, but this shouldn't be a big deal.
TIFF supports the spatial resolution tags. See the
C<tiff_resolutionunit> tag for some extra options.
+As of Imager 0.62 Imager reads:
+
+=over
+
+=item *
+
+8-bit/sample gray, RGB or CMYK images, including a possible alpha
+channel as an 8-bit/sample image.
+
+=item *
+
+16-bit gray, RGB, or CMYK image, including a possible alpha channel as
+a 16-bit/sample image.
+
+=item *
+
+32-bit gray, RGB image, including a possible alpha channel as a
+double/sample image.
+
+=item *
+
+bi-level images as paletted images containing only black and white,
+which other formats will also write as bi-level.
+
+=item *
+
+tiled paletted images are now handled correctly
+
+=item *
+
+other images are read using C<tifflib>'s RGBA interface as
+8-bit/sample images.
+
+=back
+
The following tags are set in a TIFF image when read, and can be set
to control output:
=over
-=item tiff_resolutionunit
+=item *
+
+C<tiff_compression> - When reading an image this is set to the numeric
+value of the TIFF compression tag.
+
+On writing you can set this to either a numeric compression tag value,
+or one of the following values:
+
+ Ident Number Description
+ none 1 No compression
+ packbits 32773 Macintosh RLE
+ ccittrle 2 CCITT RLE
+ fax3 3 CCITT Group 3 fax encoding (T.4)
+ t4 3 As above
+ fax4 4 CCITT Group 4 fax encoding (T.6)
+ t6 4 As above
+ lzw 5 LZW
+ jpeg 7 JPEG
+ zip 8 Deflate (GZIP) Non-standard
+ deflate 8 As above.
+ oldzip 32946 Deflate with an older code.
+ ccittrlew 32771 Word aligned CCITT RLE
+
+In general a compression setting will be ignored where it doesn't make
+sense, eg. C<jpeg> will be ignored for compression if the image is
+being written as bilevel.
+
+=for stopwords LZW
+
+Imager attempts to check that your build of C<libtiff> supports the
+given compression, and will fallback to C<packbits> if it isn't
+enabled. eg. older distributions didn't include LZW compression, and
+JPEG compression is only available if C<libtiff> is configured with
+C<libjpeg>'s location.
+
+ $im->write(file => 'foo.tif', tiff_compression => 'lzw')
+ or die $im->errstr;
-The value of the ResolutionUnit tag. This is ignored on writing if
-the i_aspect_only tag is non-zero.
+=item *
+
+C<tags, tiff_jpegquality>C<tiff_jpegquality> - If C<tiff_compression>
+is C<jpeg> then this can be a number from 1 to 100 giving the JPEG
+compression quality. High values are better quality and larger files.
+
+=item *
+
+X<tags, tiff_resolutionunit>C<tiff_resolutionunit> - The value of the
+C<ResolutionUnit> tag. This is ignored on writing if the
+i_aspect_only tag is non-zero.
The C<i_xres> and C<i_yres> tags are expressed in pixels per inch no
matter the value of this tag, they will be converted to/from the value
stored in the TIFF file.
-=item tiff_resolutionunit_name
+=item *
-This is set when reading a TIFF file to the name of the unit given by
+X<tags, tiff_resolutionunit_name>C<tiff_resolutionunit_name> - This is
+set when reading a TIFF file to the name of the unit given by
C<tiff_resolutionunit>. Possible results include C<inch>,
C<centimeter>, C<none> (the C<i_aspect_only> tag is also set reading
these files) or C<unknown>.
-=item tiff_bitspersample
-
-Bits per sample from the image. This value is not used when writing
-an image, it is only set on a read image.
-
-=item tiff_photometric
-
-Value of the PhotometricInterpretation tag from the image. This value
-is not used when writing an image, it is only set on a read image.
-
-=item tiff_documentname
-
-=item tiff_imagedescription
-
-=item tiff_make
-
-=item tiff_model
+=item *
-=item tiff_pagename
+X<tags, tiff_bitspersample>C<tiff_bitspersample> - Bits per sample
+from the image. This value is not used when writing an image, it is
+only set on a read image.
-=item tiff_software
+=item *
-=item tiff_datetime
+X<tags, tiff_photometric>C<tiff_photometric> - Value of the
+C<PhotometricInterpretation> tag from the image. This value is not
+used when writing an image, it is only set on a read image.
-=item tiff_artist
+=item *
-=item tiff_hostcomputer
+C<tiff_documentname>, C<tiff_imagedescription>, C<tiff_make>,
+C<tiff_model>, C<tiff_pagename>, C<tiff_software>, C<tiff_datetime>,
+C<tiff_artist>, C<tiff_hostcomputer> - Various strings describing the
+image. C<tiff_datetime> must be formatted as "YYYY:MM:DD HH:MM:SS".
+These correspond directly to the mixed case names in the TIFF
+specification. These are set in images read from a TIFF and saved
+when writing a TIFF image.
-Various strings describing the image. tiff_datetime must be formatted
-as "YYYY:MM:DD HH:MM:SS". These correspond directly to the mixed case
-names in the TIFF specification. These are set in images read from a
-TIFF and saved when writing a TIFF image.
+=back
You can supply a C<page> parameter to the C<read()> method to read
some page other than the first. The page is 0 based:
$image->read(file=>"example.tif", page=>1)
or die "Cannot read second page: ",$image->errstr,"\n";
-=back
+If you read an image with multiple alpha channels, then only the first
+alpha channel will be read.
-=head2 BMP (BitMaP)
+=head2 BMP (Windows Bitmap)
Imager can write 24-bit RGB, and 8, 4 and 1-bit per pixel paletted
Windows BMP files. Currently you cannot write compressed BMP files
Windows BMP files. There is some support for reading 16-bit per pixel
images, but I haven't found any for testing.
-BMP has no support for multi-image files.
+BMP has no support for multiple image files.
BMP files support the spatial resolution tags, but since BMP has no
support for storing only an aspect ratio, if C<i_aspect_only> is set
The type of compression, if any. This can be any of the following
values:
+=for stopwords RLE
+
=over
=item BI_RGB (0)
=back
-=head2 TGA (TarGA)
+=for stopwords Targa
-When storing targa images rle compression can be activated with the
-'compress' parameter, the 'idstring' parameter can be used to set the
-targa comment field and the 'wierdpack' option can be used to use the
-15 and 16 bit targa formats for rgb and rgba data. The 15 bit format
+=head2 TGA (Targa)
+
+When storing Targa images RLE compression can be activated with the
+C<compress> parameter, the C<idstring> parameter can be used to set the
+Targa comment field and the C<wierdpack> option can be used to use the
+15 and 16 bit Targa formats for RGB and RGBA data. The 15 bit format
has 5 of each red, green and blue. The 16 bit format in addition
allows 1 bit of alpha. The most significant bits are used for each
channel.
-
Tags:
=over
=head2 RAW
When reading raw images you need to supply the width and height of the
-image in the xsize and ysize options:
+image in the C<xsize> and C<ysize> options:
$img->read(file=>'foo.raw', xsize=>100, ysize=>100)
or die "Cannot read raw image\n";
If your input file has more channels than you want, or (as is common),
-junk in the fourth channel, you can use the datachannels and
-storechannels options to control the number of channels in your input
+junk in the fourth channel, you can use the C<datachannels> and
+C<storechannels> options to control the number of channels in your input
file and the resulting channels in your image. For example, if your
input image uses 32-bits per pixel with red, green, blue and junk
values for each pixel you could do:
storechannels=>3)
or die "Cannot read raw image\n";
-Normally the raw image is expected to have the value for channel 1
-immediately following channel 0 and channel 2 immediately following
-channel 1 for each pixel. If your input image has all the channel 0
-values for the first line of the image, followed by all the channel 1
-values for the first line and so on, you can use the interleave option:
+Read parameters:
+
+=over
+
+=item *
+
+raw_interleave - controls the ordering of samples within the image.
+Default: 1. Alternatively and historically spelled C<interleave>.
+Possible values:
+
+=over
+
+=item *
+
+0 - samples are pixel by pixel, so all samples for the first pixel,
+then all samples for the second pixel and so on. eg. for a four pixel
+scan line the channels would be laid out as:
+
+ 012012012012
+
+=item *
+
+1 - samples are line by line, so channel 0 for the entire scan line is
+followed by channel 1 for the entire scan line and so on. eg. for a
+four pixel scan line the channels would be laid out as:
+
+ 000011112222
+
+This is the default.
+
+=back
+
+Unfortunately, historically, the default C<raw_interleave> for read
+has been 1, while writing only supports the C<raw_interleave> = 0
+format.
- $img->read(file=>'foo.raw', xsize=100, ysize=>100, interleave=>1)
+For future compatibility, you should always supply the
+C<raw_interleave> (or C<interleave>) parameter. As of 0.68, Imager
+will warn if you attempt to read a raw image without a
+C<raw_interleave> parameter.
+
+=item *
+
+raw_storechannels - the number of channels to store in the image.
+Range: 1 to 4. Default: 3. Alternatively and historically spelled
+C<storechannels>.
+
+=item *
+
+raw_datachannels - the number of channels to read from the file.
+Range: 1 or more. Default: 3. Alternatively and historically spelled
+C<datachannels>.
+
+=back
+
+ $img->read(file=>'foo.raw', xsize=100, ysize=>100, raw_interleave=>1)
or die "Cannot read raw image\n";
=head2 PNG
There are no PNG specific tags.
+=head2 ICO (Microsoft Windows Icon) and CUR (Microsoft Windows Cursor)
+
+Icon and Cursor files are very similar, the only differences being a
+number in the header and the storage of the cursor hot spot. I've
+treated them separately so that you're not messing with tags to
+distinguish between them.
+
+The following tags are set when reading an icon image and are used
+when writing it:
+
+=over
+
+=item ico_mask
+
+This is the AND mask of the icon. When used as an icon in Windows 1
+bits in the mask correspond to pixels that are modified by the source
+image rather than simply replaced by the source image.
+
+Rather than requiring a binary bitmap this is accepted in a specific format:
+
+=over
+
+=item *
+
+first line consisting of the 0 placeholder, the 1 placeholder and a
+newline.
+
+=item *
+
+following lines which contain 0 and 1 placeholders for each scan line
+of the image, starting from the top of the image.
+
+=back
+
+When reading an image, '.' is used as the 0 placeholder and '*' as the
+1 placeholder. An example:
+
+ .*
+ ..........................******
+ ..........................******
+ ..........................******
+ ..........................******
+ ...........................*****
+ ............................****
+ ............................****
+ .............................***
+ .............................***
+ .............................***
+ .............................***
+ ..............................**
+ ..............................**
+ ...............................*
+ ...............................*
+ ................................
+ ................................
+ ................................
+ ................................
+ ................................
+ ................................
+ *...............................
+ **..............................
+ **..............................
+ ***.............................
+ ***.............................
+ ****............................
+ ****............................
+ *****...........................
+ *****...........................
+ *****...........................
+ *****...........................
+
+=back
+
+The following tags are set when reading an icon:
+
+=over
+
+=item ico_bits
+
+The number of bits per pixel used to store the image.
+
+=back
+
+For cursor files the following tags are set and read when reading and
+writing:
+
+=over
+
+=item cur_mask
+
+This is the same as the ico_mask above.
+
+=item cur_hotspotx
+
+=item cur_hotspoty
+
+The "hot" spot of the cursor image. This is the spot on the cursor
+that you click with. If you set these to out of range values they are
+clipped to the size of the image when written to the file.
+
+=back
+
+The following parameters can be supplied to read() or read_multi() to
+control reading of ICO/CUR files:
+
+=over
+
+=item *
+
+ico_masked - if true, the default, then the icon/cursors mask is
+applied as an alpha channel to the image. This may result in a
+paletted image being returned as a direct color image. Default: 1
+
+ # retrieve the image as stored, without using the mask as an alpha
+ # channel
+ $img->read(file => 'foo.ico', ico_masked => 0)
+ or die $img->errstr;
+
+This was introduced in Imager 0.60. Previously reading ICO images
+acted as if C<ico_masked =E<gt> 0>.
+
+=back
+
+C<cur_bits> is set when reading a cursor.
+
+Examples:
+
+ my $img = Imager->new(xsize => 32, ysize => 32, channels => 4);
+ $im->box(color => 'FF0000');
+ $im->write(file => 'box.ico');
+
+ $im->settag(name => 'cur_hotspotx', value => 16);
+ $im->settag(name => 'cur_hotspoty', value => 16);
+ $im->write(file => 'box.cur');
+
+=for stopwords BW
+
+=head2 SGI (RGB, BW)
+
+SGI images, often called by the extensions, RGB or BW, can be stored
+either uncompressed or compressed using an RLE compression.
+
+By default, when saving to an extension of C<rgb>, C<bw>, C<sgi>,
+C<rgba> the file will be saved in SGI format. The file extension is
+otherwise ignored, so saving a 3-channel image to a C<.bw> file will
+result in a 3-channel image on disk.
+
+The following tags are set when reading a SGI image:
+
+=over
+
+=item *
+
+i_comment - the C<IMAGENAME> field from the image. Also written to
+the file when writing.
+
+=item *
+
+sgi_pixmin, sgi_pixmax - the C<PIXMIN> and C<PIXMAX> fields from the
+image. On reading image data is expanded from this range to the full
+range of samples in the image.
+
+=item *
+
+sgi_bpc - the number of bytes per sample for the image. Ignored when
+writing.
+
+=item *
+
+sgi_rle - whether or not the image is compressed. If this is non-zero
+when writing the image will be compressed.
+
+=back
+
+=head1 ADDING NEW FORMATS
+
+To support a new format for reading, call the register_reader() class
+method:
+
+=over
+
+=item register_reader()
+
+Registers single or multiple image read functions.
+
+Parameters:
+
+=over
+
+=item *
+
+type - the identifier of the file format, if Imager's
+i_test_format_probe() can identify the format then this value should
+match i_test_format_probe()'s result.
+
+This parameter is required.
+
+=item *
+
+single - a code ref to read a single image from a file. This is
+supplied:
+
+=over
+
+=item *
+
+the object that read() was called on,
+
+=item *
+
+an Imager::IO object that should be used to read the file, and
+
+=item *
+
+all the parameters supplied to the read() method.
+
+=back
+
+The single parameter is required.
+
+=item *
+
+multiple - a code ref which is called to read multiple images from a
+file. This is supplied:
+
+=over
+
+=item *
+
+an Imager::IO object that should be used to read the file, and
+
+=item *
+
+all the parameters supplied to the read_multi() method.
+
+=back
+
+=back
+
+Example:
+
+ # from Imager::File::ICO
+ Imager->register_reader
+ (
+ type=>'ico',
+ single =>
+ sub {
+ my ($im, $io, %hsh) = @_;
+ $im->{IMG} = i_readico_single($io, $hsh{page} || 0);
+
+ unless ($im->{IMG}) {
+ $im->_set_error(Imager->_error_as_msg);
+ return;
+ }
+ return $im;
+ },
+ multiple =>
+ sub {
+ my ($io, %hsh) = @_;
+
+ my @imgs = i_readico_multi($io);
+ unless (@imgs) {
+ Imager->_set_error(Imager->_error_as_msg);
+ return;
+ }
+ return map {
+ bless { IMG => $_, DEBUG => $Imager::DEBUG, ERRSTR => undef }, 'Imager'
+ } @imgs;
+ },
+ );
+
+=item register_writer()
+
+Registers single or multiple image write functions.
+
+Parameters:
+
+=over
+
+=item *
+
+type - the identifier of the file format. This is typically the
+extension in lowercase.
+
+This parameter is required.
+
+=item *
+
+single - a code ref to write a single image to a file. This is
+supplied:
+
+=over
+
+=item *
+
+the object that write() was called on,
+
+=item *
+
+an Imager::IO object that should be used to write the file, and
+
+=item *
+
+all the parameters supplied to the write() method.
+
+=back
+
+The single parameter is required.
+
+=item *
+
+multiple - a code ref which is called to write multiple images to a
+file. This is supplied:
+
+=over
+
+=item *
+
+the class name write_multi() was called on, this is typically
+C<Imager>.
+
+=item *
+
+an Imager::IO object that should be used to write the file, and
+
+=item *
+
+all the parameters supplied to the read_multi() method.
+
+=back
+
+=back
+
+=back
+
+If you name the reader module C<Imager::File::>I<your-format-name>
+where I<your-format-name> is a fully upper case version of the type
+value you would pass to read(), read_multi(), write() or write_multi()
+then Imager will attempt to load that module if it has no other way to
+read or write that format.
+
+For example, if you create a module Imager::File::GIF and the user has
+built Imager without it's normal GIF support then an attempt to read a
+GIF image will attempt to load Imager::File::GIF.
+
+If your module can only handle reading then you can name your module
+C<Imager::File::>I<your-format-name>C<Reader> and Imager will attempt
+to autoload it.
+
+If your module can only handle writing then you can name your module
+C<Imager::File::>I<your-format-name>C<Writer> and Imager will attempt
+to autoload it.
+
+=head1 PRELOADING FILE MODULES
+
+=over
+
+=item preload()
+
+This preloads the file support modules included with or that have been
+included with Imager in the past. This is intended for use in forking
+servers such as mod_perl.
+
+If the module is not available no error occurs.
+
+Preserves $@.
+
+ use Imager;
+ Imager->preload;
+
+=back
+
=head1 EXAMPLES
=head2 Producing an image from a CGI script
Once you have an image the basic mechanism is:
+=for stopwords STDOUT
+
=over
=item 1.
If your images are RGB images the default quantization mechanism will
produce a very good result, but can take a long time to execute. You
-could either use the standard webmap:
+could either use the standard web color map:
Imager->write_multi({ file=>$filename,
type=>'gif',
make_colors=>'mediancut' },
@imgs);
-By default all of the images will use the same global colormap, which
+By default all of the images will use the same global color map, which
will produce a smaller image. If your images have significant color
differences, you may want to generate a new palette for each image:
=head1 BUGS
-When saving Gif images the program does NOT try to shave of extra
+When saving GIF images the program does NOT try to shave off extra
colors if it is possible. If you specify 128 colors and there are
-only 2 colors used - it will have a 128 colortable anyway.
+only 2 colors used - it will have a 128 color table anyway.
=head1 SEE ALSO
projects / imager.git / blobdiff