PHP imagesy() Function: Usage and Examples

Returns the height of a GdImage in pixels.

What It Does

GD provides simple pixel-level operations; Imagick provides another image-processing API with distinct requirements. This reports image pixel height rather than physical display size.

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);
$result = imagesy($im);
var_dump($result);

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');
$palette = imagecreate(40, 40);
$paletteRed = imagecolorallocate($palette, 255, 0, 0);
imagecolorallocate($palette, 0, 0, 255);
$result = imagesy($palette);
var_dump($result);

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);
$dimension = imagesy($im);
if ($dimension > 1000) throw new RuntimeException("Image exceeds size policy");
echo $dimension;

For production, apply the compatibility and edge-case limits described below.

Important Behavior and Edge Cases

This reports image pixel height rather than physical display size.

Comparison with Related Functions and Tools

Common Beginner Mistakes

Key Takeaways

• Returns the height of a GdImage in pixels.
• This reports image pixel height rather than physical display size.
• 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.