(PHP 7 >= 7.2.0, PHP 8)
imageresolution — Get or set the resolution of the image
imageresolution() allows to set and get the resolution of
an image in DPI (dots per inch). If the optional parameters are null,
the current resolution is returned as an indexed array. If only
resolution_x is not null, the horizontal and vertical resolution
are set to this value. If none of the optional parameters are null, the horizontal
and vertical resolution are set to these values, respectively.
The resolution is only used as meta information when images are read from and written to formats supporting this kind of information (curently PNG and JPEG). It does not affect any drawing operations. The default resolution for new images is 96 DPI.
imageA GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
resolution_xThe horizontal resolution in DPI.
resolution_yThe vertical resolution in DPI.
When used as getter,
it returns an indexed array of the horizontal and vertical resolution on
success, or false on failure.
When used as setter, it returns
true on success, or false on failure.
| Version | Description |
|---|---|
| 8.0.0 |
resolution_x and resolution_y are now nullable.
|
Example #1 Setting and getting the resolution of an image
<?php
$im = imagecreatetruecolor(100, 100);
imageresolution($im, 200);
print_r(imageresolution($im));
imageresolution($im, 300, 72);
print_r(imageresolution($im));
?>The above example will output:
Array
(
[0] => 200
[1] => 200
)
Array
(
[0] => 300
[1] => 72
)
It should be clear that the set version of the function doesn't change the image it self, just the resource in memory, which probably is fine if you didn't save the image yet. If your use case is for an image that is already on disk, image you should always do something like:
imageresolution($img, 300, 300);
imagepng($img, $filname, $quality);