gaussian stddev
- gradgen xo yo colors dist
+ gradgen xo yo colors
+ dist 0
hardinvert
truncate the range by the specified fraction at the top and bottom of
the range respectivly.
+ # increase contrast, losing little detail
+ my $levels = $img->filter(type=>"autolevels");
+
+ # increase contrast, losing 20% of highlight at top and bottom range
+ my $trunc_levels = $img->filter(type=>"autolevels", lsat=>0.2, usat=>0.2);
+
=item bumpmap
uses the channel I<elevation> image I<bump> as a bumpmap on your
image, with the light at (I<lightx>, I<lightty>), with a shadow length
of I<st>.
+ my $shadowed = $img->filter(type=>"bumpmap", bump=>$bumpmap_img,
+ lightx=>10, lighty=>10, st=>5);
+
=item bumpmap_complex
uses the channel I<channel> image I<bump> as a bumpmap on your image.
coefficient and I<cs> is the specular coefficient. I<n> is the
shininess of the surface.
+ my $shadowed = $img->filter(type=>"bumpmap_complex", bump=>$bumpmap_img);
+
=item contrast
scales each channel by I<intensity>. Values of I<intensity> < 1.0
will reduce the contrast.
+ my $high_contrast = $img->filter(type=>"contrast", intensity=>1.3);
+ my $low_contrast = $img->filter(type=>"contrast", intensity=>0.8);
+
=item conv
performs 2 1-dimensional convolutions on the image using the values
-from I<coef>. I<coef> should be have an odd length.
+from I<coef>. I<coef> should be have an odd length and the sum of the
+coefficients must be non-zero.
+
+ my $sharper = $img->filter(type=>"conv", coef=>[-0.5, 2, -0.5 ]);
+ my $blur = $img->filter(type=>"conv", coef=>[ 1, 2, 1 ]);
=item fountain
parts of the range 0 through 1 that aren't covered by a segment), if
any segments of your fill have any transparency, you can set the
I<combine> option to 'normal' to have the fill combined with the
-existing pixels. See the description of I<combine> in L<Imager/Fill>.
+existing pixels. See the description of I<combine> in L<Imager::Fill>.
If your fill has sharp edges, for example between steps if you use
repeat set to 'triangle', you may see some aliased or ragged edges.
the type of sampling.
The segments option is an arrayref of segments. You really should use
-the Imager::Fountain class to build your fountain fill. Each segment
-is an array ref containing:
+the L<Imager::Fountain> class to build your fountain fill. Each
+segment is an array ref containing:
=over
=item start
-a floating point number between 0 and 1, the start of the range of fill parameters covered by this segment.
+a floating point number between 0 and 1, the start of the range of
+fill parameters covered by this segment.
=item middle
http://www.maths.abdn.ac.uk/~igc/tch/mx4002/notes/node99.html
+Values of C<stddev> around 0.5 provide a barely noticable blur, values
+around 5 provide a very strong blur.
+
+ my $slight_blur = $img->filter(type=>"gaussian", stddev=>0.5);
+ my $blurry = $img->filter(type=>"gaussian", stddev=>5);
+
=item gradgen
renders a gradient, with the given I<colors> at the corresponding
points (x,y) in I<xo> and I<yo>. You can specify the way distance is
-measured for color blendeing by setting I<dist> to 0 for Euclidean, 1
+measured for color blending by setting I<dist> to 0 for Euclidean, 1
for Euclidean squared, and 2 for Manhattan distance.
+ my $redbluegreen = $img->filter
+ (type="gradgen", xo=>[ 10, 50, 10 ], yo=>[ 10, 50, 50 ],
+ colors=>[ qw(red blue green) ]);
+
=item hardinvert
inverts the image, black to white, white to black. All channels are
inverted, including the alpha channel if any.
+ my $inverted = $img->filter(type=>"hardinvert");
+
=item mosaic
produces averaged tiles of the given I<size>.
+ my $mosaic = $img->filter(type=>"mosaic", size=>5);
+
=item noise
adds noise of the given I<amount> to the image. If I<subtype> is
zero, the noise is even to each channel, otherwise noise is added to
each channel independently.
+ my $mono_noise = $img->filter(type=>"noise", amount=>20, subtype=>0);
+ my $color_noise = $img->filter(type=>"noise", amount=>20, subtype=>1);
+
=item radnoise
renders radiant Perlin turbulent noise. The centre of the noise is at
(I<xo>, I<yo>), I<ascale> controls the angular scale of the noise ,
and I<rscale> the radial scale, higher numbers give more detail.
+ my $radial_noise = $img->filter(type=>"radnoise", xo=>50, yo=>50,
+ ascale=>1, rscale=>0.02);
+
=item postlevels
alters the image to have only I<levels> distinct level in each
channel.
+ my $posted = $img->filter(type=>"postlevels", levels=>10);
+
=item turbnoise
renders Perlin turbulent noise. (I<xo>, I<yo>) controls the origin of
the noise, and I<scale> the scale of the noise, with lower numbers
giving more detail.
+ my $noise = $img->filter(type=>"turbnoise", xo=>10, yo=>10, scale=>10);
+
=item unsharpmask
performs an unsharp mask on the image. This is the result of
I<stddev> controls the stddev parameter of the gaussian blur. Each
output pixel is: in + I<scale> * (in - blurred).
+ my $unsharp = $img->filter(type=>"unsharpmask", stddev=>1, scale=>0.5);
+
=item watermark
applies I<wmark> as a watermark on the image with strength I<pixdiff>,
with an origin at (I<tx>, I<ty>)
+ my $marked = $img->filter(type=>"watermark", tx=>10, ty=>50,
+ wmark=>$wmark_image, pixdiff=>50);
+
=back
A demonstration of most of the filters can be found at:
projects / imager.git / commitdiff