Reads the signature bytes of an image to identify its format, without decoding the full raster.
What It Does
getimagesize() reads dimensions; EXIF functions inspect metadata or image signatures. A recognized signature is not proof that an upload is safe or that GD can decode the file.
Requirements and Compatibility
EXIF 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 (!is_file(__DIR__ . '/photo.jpg')) throw new RuntimeException('Provide the sample file /photo.jpg');
$result = exif_imagetype(__DIR__ . '/photo.jpg');
var_dump($result);Example 2: Another Case
Change the inputs to observe the behavior on another case.
<?php
if (!is_file(__DIR__ . '/logo.png')) throw new RuntimeException('Provide the sample file /logo.png');
$result = exif_imagetype(__DIR__ . '/logo.png');
var_dump($result);Practical Example
Use the result to create an output, validate a condition, or complete an image workflow.
<?php
$path = __DIR__ . '/photo.jpg';
if (!is_file($path)) throw new RuntimeException('Missing sample');
$info = exif_imagetype(__DIR__ . '/photo.jpg');
if ($info === false) throw new RuntimeException('Invalid metadata');
print_r($info);For production, apply the compatibility and edge-case limits described below.
Important Behavior and Edge Cases
A recognized signature is not proof that an upload is safe or that GD can decode the file.
Comparison with Related Functions and Tools
| Subject | Key difference |
|---|---|
| exif_imagetype() | getimagesize() reads dimensions; EXIF functions inspect metadata or image signatures. |
Common Beginner Mistakes
| Mistake | Correct approach |
|---|---|
| Calling exif_imagetype() without its required input or supported extension | Check the extension, supply valid arguments, and handle false or exceptions according to the function. |
| Assuming exif_imagetype() guarantees a valid or safe image | A recognized signature is not proof that an upload is safe or that GD can decode the file. |
| Confusing the operation with a related API | getimagesize() reads dimensions; EXIF functions inspect metadata or image signatures. |
Key Takeaways
- Reads the signature bytes of an image to identify its format, without decoding the full raster.
- A recognized signature is not proof that an upload is safe or that GD can decode the file.
- 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.