$newimg = $img->copy();
- $newimg = $img->scale(xpixels=>400);
+ $newimg = $img->scale(xpixels=>400, qtype => 'mixing');
$newimg = $img->scale(xpixels=>400, ypixels=>400);
- $newimg = $img->scale(xpixels=>400, ypixels=>400, type=>min);
+ $newimg = $img->scale(xpixels=>400, ypixels=>400, type=>'min');
$newimg = $img->scale(scalefactor=>0.25);
+ $newimg = $img->scaleX(pixels=>400);
+ $newimg = $img->scaleX(scalefactor=>0.25);
+ $newimg = $img->scaleY(pixels=>400);
+ $newimg = $img->scaleY(scalefactor=>0.25);
+
$newimg = $img->crop(left=>50, right=>100, top=>10, bottom=>100);
$newimg = $img->crop(left=>50, top=>10, width=>50, height=>90);
$dest->paste(left=>40,top=>20,img=>$logo);
- $img->rubthrough(src=>$srcimage,tx=>30,ty=>50);
+ $img->rubthrough(src=>$srcimage,tx=>30, ty=>50);
+ $img->rubthrough(src=>$srcimage,tx=>30, ty=>50,
+ src_minx=>20, src_miny=>30,
+ src_maxx=>20, src_maxy=>30);
$img->flip(dir=>"h"); # horizontal flip
=item scale
-To scale an image so porportions are maintained use the
+X<scale>To scale an image so porportions are maintained use the
C<$img-E<gt>scale()> method. if you give either a xpixels or ypixels
parameter they will determine the width or height respectively. If
-both are given the one resulting in a larger image is used. example:
-C<$img> is 700 pixels wide and 500 pixels tall.
+both are given the one resulting in a larger image is used, unless you
+set the C<type> parameter to C<'min'>. example: C<$img> is 700 pixels
+wide and 500 pixels tall.
$newimg = $img->scale(xpixels=>400); # 400x285
$newimg = $img->scale(ypixels=>400); # 560x400
$newimg = $img->scale(xpixels=>400,ypixels=>400); # 560x400
- $newimg = $img->scale(xpixels=>400,ypixels=>400,type=>min); # 400x285
+ $newimg = $img->scale(xpixels=>400,ypixels=>400,type=>'min'); # 400x285
+
+ $newimg = $img->scale(xpixels=>400, ypixels=>400),type=>'nonprop'); # 400x400
$newimg = $img->scale(scalefactor=>0.25); 175x125
$newimg = $img->scale(); # 350x250
-if you want to create low quality previews of images you can pass
+If you want to create low quality previews of images you can pass
C<qtype=E<gt>'preview'> to scale and it will use nearest neighbor
sampling instead of filtering. It is much faster but also generates
worse looking images - especially if the original has a lot of sharp
variations and the scaled image is by more than 3-5 times smaller than
the original.
-If you need to scale images per axis it is best to do it simply by
-calling scaleX and scaleY. You can pass either 'scalefactor' or
-'pixels' to both functions.
+=over
+
+=item *
+
+xpixels, ypixels - desired size of the scaled image. The C<type>
+parameter controls whether the larger or smaller of the two possible
+sizes is chosen, or if the image is scaled non-proportionally.
+
+=item *
+
+constrain - an Image::Math::Constrain object defining the way in which
+the image size should be constrained.
+
+=item *
+
+scalefactor - if none of xpixels, ypixels, xscalefactor, yscalefactor
+or constrain is supplied then this is used as the ratio to scale by.
+Default: 0.5.
+
+=item *
+
+xscalefactor, yscalefactor - if both are supplied then the image is
+scaled as per these parameters, whether this is proportionally or not.
+New in Imager 0.54.
+
+=item *
+
+type - controls whether the larger or smaller of the two possible
+sizes is chosen, possible values are:
+
+=over
+
+=item *
+
+min - the smaller of the 2 sizes are chosen.
+
+=item *
+
+max - the larger of the 2 sizes. This is the default.
+
+=item *
+
+nonprop - non-proportional scaling. New in Imager 0.54.
+
+=back
+
+scale() will fail if C<type> is set to some other value.
+
+For example, if the original image is 400 pixels wide by 200 pixels
+high and C<xpixels> is set to 300, and C<ypixels> is set to 160. When
+C<type> is C<'min'> the resulting image is 300 x 150, when C<type> is
+C<'max'> the resulting image is 320 x 150.
+
+C<type> is only used if both C<xpixels> and C<ypixels> are supplied.
+
+=item *
+
+qtype - defines the quality of scaling performed. Possible values are:
+
+=over
+
+=item *
+
+C<normal> - high quality scaling. This is the default.
+
+=item *
+
+C<preview> - lower quality. When scaling down this will skip input
+pixels, eg. scaling by 0.5 will skip every other pixel. When scaling
+up this will duplicate pixels.
+
+=item *
+
+C<mixing> - implements the mixing algorithm implemented by pnmscale.
+This retains more detail when scaling down than C<normal>. When
+scaling down this proportionally accumulates sample data from the
+pixels, resulting in a proportional mix of all of the pixels. When
+scaling up this will mix pixels when the sampling grid crosses a pixel
+boundary but will otherwise copy pixel values.
+
+=back
+
+scale() will fail if C<qtype> is set to some other value.
+
+C<preview> is faster than C<mixing> which is much faster than C<normal>.
+
+=back
+
+To scale an image on a given axis without maintaining proportions, it
+is best to call the scaleX() and scaleY() methods with the required
+dimensions. eg.
+
+ my $scaled = $img->scaleX(pixels=>400)->scaleY(pixels=>200);
+
+From Imager 0.54 you can scale without maintaining proportions either
+by supplying both the xscalefactor and yscalefactor arguments:
+
+ my $scaled = $img->scale(xscalefactor => 0.5, yscalefactor => 0.67);
+
+or by supplying C<xpixels> and C<ypixels> and setting C<type> to
+"nonprop":
+
+ my $scaled = $im->scale(xpixels => 200, ypixels => 200, type => 'nonprop');
+
+Returns a new scaled image on success. The source image is not
+modified.
+
+Returns false on failure, check the errstr() method for the reason for
+failure.
+
+A mandatory warning is produced if scale() is called in void context.
+
+ # setup
+ my $image = Imager->new;
+ $image->read(file => 'somefile.jpg')
+ or die $image->errstr;
+
+ # all full quality unless indicated otherwise
+ # half the size:
+ my $half = $image->scale;
+
+ # double the size
+ my $double = $image->scale(scalefactor => 2.0);
+
+ # so a 400 x 400 box fits in the resulting image:
+ my $fit400x400inside = $image->scale(xpixels => 400, ypixels => 400);
+ my $fit400x400inside2 = $image->scale(xpixels => 400, ypixels => 400,
+ type=>'max');
+
+ # fit inside a 400 x 400 box
+ my $inside400x400 = $image->scale(xpixels => 400, ypixels => 400,
+ type=>'min');
+
+ # make it 400 pixels wide or high
+ my $width400 = $image->scale(xpixels => 400);
+ my $height400 = $image->scale(ypixels => 400);
+
+ # low quality scales:
+ # to half size
+ my $low = $image->scale(qtype => 'preview');
+
+ # mixing method scale
+ my $mixed = $image->scale(qtype => 'mixing', scalefactor => 0.1);
+
+ # using an Image::Math::Constrain object
+ use Image::Math::Constrain;
+ my $constrain = Image::Math::Constrain->new(800, 600);
+ my $scaled = $image->scale(constrain => $constrain);
+
+ # same as Image::Math::Constrain version
+ my $scaled2 = $image->scale(xpixels => 800, ypixels => 600, type => 'min');
+
+=item scaleX
+
+scaleX() will scale along the X dimension, return a new image with the
+new width:
+
+ my $newimg = $img->scaleX(pixels=>400); # 400x500
+ $newimg = $img->scaleX(scalefactor=>0.25) # 175x500
+
+=over
+
+=item *
+
+scalefactor - the amount to scale the X axis. Ignored if C<pixels> is
+provided. Default: 0.5.
+
+=item *
+
+pixels - the new width of the image.
+
+=back
+
+Returns a new scaled image on success. The source image is not
+modified.
+
+Returns false on failure, check the errstr() method for the reason for
+failure.
+
+A mandatory warning is produced if scaleX() is called in void context.
+
+=item scaleY
+
+scaleY() will scale along the Y dimension, return a new image with the
+new height:
+
+ $newimg = $img->scaleY(pixels=>400); # 700x400
+ $newimg = $img->scaleY(scalefactor=>0.25) # 700x125
+
+=over
+
+=item *
+
+scalefactor - the amount to scale the Y axis. Ignored if C<pixels> is
+provided. Default: 0.5.
+
+=item *
+
+pixels - the new height of the image.
+
+=back
+
+Returns a new scaled image on success. The source image is not
+modified.
+
+Returns false on failure, check the errstr() method for the reason for
+failure.
+
+A mandatory warning is produced if scaleY() is called in void context.
+
+=item scale_calculate
+
+Performs the same calculations that the scale() method does to
+calculate the scaling factors from the parameters you pass.
+
+scale_calculate() can be called as an object method, or as a class
+method.
+
+Takes the following parameters over scale():
+
+=over
+
+=item *
+
+width, height - the image width and height to base the scaling on.
+Required if scale_calculate() is called as a class method. If called
+as an object method these default to the image width and height
+respectively.
+
+=back
+
+You might use scale_calculate() as a class method when generating an
+IMG tag, for example.
+
+Returns an empty list on failure.
+
+Returns a list containing horizontal scale factor, vertical scale
+factor, new width, new height, on success.
+
+ my ($x_scale, $y_scale, $new_width, $new_height) =
+ Imager->scale_calculate(width => 1024, height => 768,
+ ypixels => 180, type => 'min');
+
+ my ($x_scale, $y_scale, $new_width, $new_height) =
+ $img->scale_calculate(xpixels => 200, type => 'min');
=item crop
+Another way to resize an image is to crop it. The parameters to
+crop are the edges of the area that you want in the returned image,
+where the right and bottom edges are non-inclusive. If a parameter is
+omitted a default is used instead.
+
+crop() returns the cropped image and does not modify the source image.
+
+The possible parameters are:
+
+=over
+
+=item *
+
+C<left> - the left edge of the area to be cropped. Default: 0
+
+=item *
+
+C<top> - the top edge of the area to be cropped. Default: 0
+
+=item *
+
+C<right> - the right edge of the area to be cropped. Default: right
+edge of image.
+
+=item *
+
+C<bottom> - the bottom edge of the area to be cropped. Default:
+bottom edge of image.
+
+=item *
+
+C<width> - width of the crop area. Ignored if both C<left> and C<right> are
+supplied. Centered on the image if neither C<left> nor C<right> are
+supplied.
+
+=item *
+
+C<height> - height of the crop area. Ignored if both C<top> and
+C<bottom> are supplied. Centered on the image if neither C<top> nor
+C<bottom> are supplied.
+
+=back
-Another way to resize an image size is to crop it. The parameters
-to crop are the edges of the area that you want in the returned image.
-If a parameter is omited a default is used instead.
+For example:
+ # these produce the same image
$newimg = $img->crop(left=>50, right=>100, top=>10, bottom=>100);
$newimg = $img->crop(left=>50, top=>10, width=>50, height=>90);
- $newimg = $img->crop(left=>50, right=>100); # top
+ $newimg = $img->crop(right=>100, bottom=>100, width=>50, height=>90);
+
+ # and the following produce the same image
+ $newimg = $img->crop(left=>50, right=>100);
+ $newimg = $img->crop(left=>50, right=>100, top=>0,
+ bottom=>$img->getheight);
+
+ # grab the top left corner of the image
+ $newimg = $img->crop(right=>50, bottom=>50);
You can also specify width and height parameters which will produce a
new image cropped from the center of the input image, with the given
$newimg = $img->crop(width=>50, height=>50);
-The width and height parameters take precedence over the left/right
-and top/bottom parameters respectively.
+If you supply C<left>, C<width> and C<right> values, the C<right>
+value will be ignored. If you supply C<top>, C<height> and C<bottom>
+values, the C<bottom> value will be ignored.
-=item rotate
+The edges of the cropped area default to the edges of the source
+image, for example:
+ # a vertical bar from the middle from top to bottom
+ $newimg = $img->crop(width=>50);
+
+ # the right half
+ $newimg = $img->crop(left=>$img->getwidth() / 2);
+
+If the resulting image would have zero width or height then crop()
+returns false and $img->errstr is an appropriate error message.
+
+A mandatory warning is produced if crop() is called in void context.
+
+=item rotate
Use the rotate() method to rotate an image. This method will return a
new, rotated image.
my $rotpi4 = $img->rotate(radians=>3.14159265/4);
Exact image rotation uses the same underlying transformation engine as
-the matrix_transform() method.
+the matrix_transform() method (see Imager::Engines).
+
+You can also supply a C<back> argument which acts as a background
+color for the areas of the image with no samples available (outside
+the rectangle of the source image.) This can be either an
+Imager::Color or Imager::Color::Float object. This is B<not> mixed
+transparent pixels in the middle of the source image, it is B<only>
+used for pixels where there is no corresponding pixel in the source
+image.
To rotate in steps of 90 degrees, use the 'right' parameter:
Rotations are clockwise for positive values.
+Parameters:
+
+=over
+
+=item *
+
+right - rotate by an exact multiple of 90 degrees, specified in
+degreess.
+
+=item *
+
+radians - rotate by an angle specified in radians.
+
+=item *
+
+degrees - rotate by an angle specified in degrees.
+
+=item *
+
+back - for C<radians> and C<degrees> this is the color used for the
+areas not covered by the original image. For example, the corners of
+an image rotated by 45 degrees.
+
+This can be either an Imager::Color object, an Imager::Color::Float
+object or any parameter that Imager can convert to a color object, see
+L<Imager::Draw/Color Parameters> for details.
+
+This is B<not> mixed transparent pixels in the middle of the source
+image, it is B<only> used for pixels where there is no corresponding
+pixel in the source image.
+
+Default: transparent black.
+
=back
+ # rotate 45 degrees clockwise,
+ my $rotated = $img->rotate(degrees => 45);
-=head2 Image pasting/flipping/
+ # rotate 10 degrees counter-clockwise
+ # set pixels not sourced from the original to red
+ my $rotated = $img->rotate(degrees => -10, back => 'red');
+
+=back
+
+=head2 Image pasting/flipping
A list of the transformations that alter the source image follows:
=item paste
+X<paste>To copy an image to onto another image use the C<paste()>
+method.
-To copy an image to onto another image use the C<paste()> method.
-
- $dest->paste(left=>40,top=>20,img=>$logo);
+ $dest->paste(left=>40, top=>20, src=>$logo);
That copies the entire C<$logo> image onto the C<$dest> image so that the
upper left corner of the C<$logo> image is at (40,20).
+Parameters:
+
+=over
+
+=item *
+
+src, img - the source image. I<src> added for compatibility with
+rubthrough().
+
+=item *
+
+left, top - position in output of the top left of the pasted image.
+Default: (0,0)
+
+=item *
+
+src_minx, src_miny - the top left corner in the source image to start
+the paste from. Default: (0, 0)
+=item *
+
+src_maxx, src_maxy - the bottom right in the source image of the sub
+image to paste. This position is B<non> inclusive. Default: bottom
+right corner of the source image.
+
+=item *
+
+width, height - if the corresponding src_maxx or src_maxy is not
+defined then width or height is used for the width or height of the
+sub image to be pasted.
+
+=back
+
+ # copy the 20x20 pixel image from (20,20) in $src_image to (10,10) in $img
+ $img->paste(src=>$src_image,
+ left => 10, top => 10,
+ src_minx => 20, src_miny => 20,
+ src_maxx => 40, src_maxx => 40);
+
=item rubthrough
A more complicated way of blending images is where one image is
put 'over' the other with a certain amount of opaqueness. The
method that does this is rubthrough.
- $img->rubthrough(src=>$srcimage,tx=>30,ty=>50);
+ $img->rubthrough(src=>$overlay,
+ tx=>30, ty=>50,
+ src_minx=>20, src_miny=>30,
+ src_maxx=>20, src_maxy=>30);
+
+That will take the sub image defined by I<$overlay> and
+I<[src_minx,src_maxx)[src_miny,src_maxy)> and overlay it on top of
+I<$img> with the upper left corner at (30,50). You can rub 2 or 4
+channel images onto a 3 channel image, or a 2 channel image onto a 1
+channel image. The last channel is used as an alpha channel. To add
+an alpha channel to an image see I<convert()>.
-That will take the image C<$srcimage> and overlay it with the upper
-left corner at (30,50). You can rub 2 or 4 channel images onto a 3
-channel image, or a 2 channel image onto a 1 channel image. The last
-channel is used as an alpha channel.
+Parameters:
+=over
+
+=item *
+
+tx, ty - location in the the target image ($self) to render the top
+left corner of the source.
+
+=item *
+
+src_minx, src_miny - the top left corner in the source to transfer to
+the target image. Default: (0, 0).
+
+=item *
+
+src_maxx, src_maxy - the bottom right in the source image of the sub
+image to overlay. This position is B<non> inclusive. Default: bottom
+right corner of the source image.
+
+=back
+
+ # overlay all of $source onto $targ
+ $targ->rubthrough(tx => 20, ty => 25, src => $source);
+
+ # overlay the top left corner of $source onto $targ
+ $targ->rubthrough(tx => 20, ty => 25, src => $source,
+ src_maxx => 20, src_maxy => 20);
+
+ # overlay the bottom right corner of $source onto $targ
+ $targ->rubthrough(tx => 20, ty => 30, src => $src,
+ src_minx => $src->getwidth() - 20,
+ src_miny => $src->getheight() - 20);
+
+rubthrough() returns true on success. On failure check
+$target->errstr for the reason for failure.
=item flip
$img->flip(dir=>"vh"); # vertical and horizontal flip
$nimg = $img->copy->flip(dir=>"v"); # make a copy and flip it vertically
-=back
+flip() returns true on success. On failure check $img->errstr for the
+reason for failure.
+=back
+=head2 Color transformations
+=over
-=head2 Color transformations
+=item convert
You can use the convert method to transform the color space of an
image using a matrix. For ease of use some presets are provided.
$new = $img->convert(matrix=>[ [ 0.333, 0.333, 0.334 ] ])
+Convert a 2 channel image (grayscale with alpha) to an RGBA image with
+the grey converted to the specified RGB color:
+
+ # set (RGB) scaled on the grey scale portion and copy the alpha
+ # channel as is
+ my $colored = $gray->convert(matrix=>[ [ ($red/255), 0 ],
+ [ ($green/255), 0 ],
+ [ ($blue/255), 0 ],
+ [ 0, 1 ],
+ ]);
+
+To convert a 3 channel image to a 4 channel image with a 50 percent
+alpha channel:
+
+ my $withalpha = $rgb->convert(matrix =>[ [ 1, 0, 0, 0 ],
+ [ 0, 1, 0, 0 ],
+ [ 0, 0, 1, 0 ],
+ [ 0, 0, 0, 0.5 ],
+ ]);
+
+=back
=head2 Color Mappings
+=over
+
+=item map
+
You can use the map method to map the values of each channel of an
image independently using a list of lookup tables. It's important to
realize that the modification is made inplace. The function simply
$img->map(maps=>[\@redmap, [], \@bluemap]);
+=back
+
+=head1 SEE ALSO
+
+L<Imager>, L<Imager::Engines>
+
+=head1 AUTHOR
+Tony Cook <tony@imager.perl.org>, Arnar M. Hrafnkelsson
+=head1 REVISION
+$Revision$
+=cut
projects / imager.git / blobdiff