PHP: imageresolution

PHP: imageresolution - Manual

(PHP 7 >= 7.2.0, PHP 8)

imageresolution — Get or set the resolution of the image

Description

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.

Parameters

image: A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
resolution_x: The horizontal resolution in DPI.
resolution_y: The vertical resolution in DPI.

Return Values

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.

Changelog

Version	Description
8.0.0	`resolution_x` and `resolution_y` are now nullable.

Examples

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
)

Found A Problem?

fernando dot fonseca at afteryou dot pt ¶

4 years ago

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);