Copies and smoothly resizes a source rectangle into a destination image.
What It Does
imagecopy() does not resize; imagecopyresampled() performs smooth resampling. For photos this usually produces better scaled results than imagecopyresized().
Requirements and Compatibility
GD extension. Sample images and fonts referred to by filename must be supplied locally. Use PHP 8 GdImage objects where applicable; optional decoders depend on the installed build.
Syntax, Inputs and Results
The arguments shown below are concrete values for this function; their types and ranges matter. The example checks return data rather than assuming that every operation succeeds.
Example 1: Basic Use
Call the function with a concrete input and inspect its result.
<?php
if (!extension_loaded('gd')) throw new RuntimeException('GD extension required');
$im = imagecreatetruecolor(160, 110);
$white = imagecolorallocate($im, 255, 255, 255);
imagefilledrectangle($im, 0, 0, 159, 109, $white);
$src = imagecreatetruecolor(40, 40);
imagefilledrectangle($src, 0, 0, 39, 39, imagecolorallocate($src, 200, 65, 60));
imageline($src, 0, 0, 39, 39, imagecolorallocate($src, 255, 255, 255));
$ok = imagecopyresampled($im, $src, 0, 0, 0, 0, 80, 80, 40, 40);
var_dump($ok);Example 2: Another Case
Change the inputs to observe the behavior on another case.
<?php
if (!extension_loaded('gd')) throw new RuntimeException('GD extension required');
$im = imagecreatetruecolor(160, 110);
$white = imagecolorallocate($im, 255, 255, 255);
imagefilledrectangle($im, 0, 0, 159, 109, $white);
$src = imagecreatetruecolor(40, 40);
imagefilledrectangle($src, 0, 0, 39, 39, imagecolorallocate($src, 200, 65, 60));
imageline($src, 0, 0, 39, 39, imagecolorallocate($src, 255, 255, 255));
$ok = imagecopyresampled($im, $src, 5, 5, 0, 0, 90, 60, 40, 40);
var_dump($ok);Practical Example
Use the result to create an output, validate a condition, or complete an image workflow.
<?php
if (!extension_loaded('gd')) throw new RuntimeException('GD extension required');
$im = imagecreatetruecolor(160, 110);
$white = imagecolorallocate($im, 255, 255, 255);
imagefilledrectangle($im, 0, 0, 159, 109, $white);
$src = imagecreatetruecolor(40, 40);
imagefilledrectangle($src, 0, 0, 39, 39, imagecolorallocate($src, 200, 65, 60));
imageline($src, 0, 0, 39, 39, imagecolorallocate($src, 255, 255, 255));
imagecopyresampled($im, $src, 5, 5, 0, 0, 90, 60, 40, 40);
if (!imagepng($im, __DIR__ . "/imagecopyresampled-demo.png")) throw new RuntimeException("Unable to save");For production, apply the compatibility and edge-case limits described below.
Important Behavior and Edge Cases
For photos this usually produces better scaled results than imagecopyresized().
Comparison with Related Functions and Tools
| Subject | Key difference |
|---|---|
| imagecopyresampled() | imagecopy() does not resize; imagecopyresampled() performs smooth resampling. |
Common Beginner Mistakes
| Mistake | Correct approach |
|---|---|
| Calling imagecopyresampled() without its required input or supported extension | Check the extension, supply valid arguments, and handle false or exceptions according to the function. |
| Assuming imagecopyresampled() guarantees a valid or safe image | For photos this usually produces better scaled results than imagecopyresized(). |
| Confusing the operation with a related API | imagecopy() does not resize; imagecopyresampled() performs smooth resampling. |
Key Takeaways
- Copies and smoothly resizes a source rectangle into a destination image.
- For photos this usually produces better scaled results than imagecopyresized().
- Choose the companion API described in the comparison table when the job differs.
Use these examples as a starting point, then validate the result with the actual PHP build, dependencies and inputs used by your application.