YouTipPhp Image Gd
# PHP Image Processing
PHP provides a rich set of image processing functions, mainly including:
| Function | Description |
| --- | --- |
| [gd_info()](#) | Gets information about the currently installed GD library |
| [getimagesize()](#) | Gets image information |
| [getimagesizefromstring()](#) | Gets image information from a string |
| [image_type_to_extension()](#) | Gets the image file extension |
| [image_type_to_mime_type()](#) | Returns the MIME type of the image |
| [image2wbmp()](#) | Outputs a WBMP image |
| [imageaffine()](#) | Returns an image after an affine transformation |
| [imageaffinematrixconcat()](#) | Concatenates two matrices |
| [imageaffinematrixget()](#) | Gets a matrix |
| [imagealphablending()](#) | Sets the blending mode for the image |
| [imageantialias()](#) | Sets or checks if antialiasing is used |
| [imagearc()](#) | Draws an elliptical arc |
| [imagechar()](#) | Draws a character horizontally |
| [imagecharup()](#) | Draws a character vertically |
| [imagecolorallocate()](#) | Allocates a color for an image |
| [imagecolorallocatealpha()](#) | Allocates a color with transparency for an image |
| [imagecolorat()](#) | Gets the color index of a pixel |
| [imagecolorclosest()](#) | Gets the index of the closest color to the specified color |
| [imagecolorclosestalpha()](#) | Gets the index of the closest color with alpha to the specified color |
| [imagecolorclosesthwb()](#) | Gets the index of the closest hue, white, and black to the specified color |
| [imagesx() and imagesy()](#) | Gets the width and height of the image |
## GD Library
To use PHP image processing functions, you need to load the GD support library. Please ensure that php.ini has loaded the GD library:
On Windows servers:
```ini
extension = php_gd2.dll
On Linux and Mac systems:
```ini
extension = php_gd2.so
You can use the `gd_info()` function to view information about the currently installed GD library:
```php
The output is roughly as follows:
array(12) {
=>
string(26) "bundled (2.1.0 compatible)"
=>
bool(true)
=>
string(13) "with freetype"
=>
bool(false)
["GIF