Scaling Images
There are two ways to change the size of an image. The
ImageCopyResized( )
function is
available in all versions of GD, but its resizing algorithm is crude and
may lead to jagged edges in your new images. The ImageCopyResampled( )
function is new in GD
2.x and features pixel interpolation to give smooth edges and clarity to
resized images (it is, however, slower than ImageCopyResized( )
). Both functions take the
same arguments:
ImageCopyResized(dest
,src
,dx
,dy
,sx
,sy
,dw
,dh
,sw
,sh
); ImageCopyResampled(dest
,src
,dx
,dy
,sx
,sy
,dw
,dh
,sw
,sh
);
The dest
and
src
parameters are image handles. The point
(
dx
,
dy
)
is the point in the destination
image where the region will be copied. The point (
sx
,
sy
)
is the upper-left corner of the source
image. The sw
, sh
,
dw
, and dh
parameters give the width and height of the copy regions in the source
and destination.
Example 9-11 takes the php.jpg image shown in Figure 9-9 and smoothly scales it down to one-quarter of its size, yielding the image in Figure 9-10.
<?php $src = ImageCreateFromJPEG('php.jpg'); $width = ImageSx($src); $height = ImageSy($src); $x = $width/2; $y = $height/2; $dst = ImageCreateTrueColor($x,$y); ImageCopyResampled($dst,$src,0,0,0,0,$x,$y,$width,$height); header('Content-Type: image/png'); ImagePNG($dst); ?>
The output ...
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