PHP provides a wealth of image processing functions, mainly including:
| function | describe |
|---|---|
| gd_info() | Get information about the currently installed GD library |
| getimagesize() | Get image information |
| getimagesizefromstring() | Get image information |
| image_type_to_extension() | Get image suffix |
| image_type_to_mime_type() | Returns the MIME type of the image |
| image2wbmp() | Output WBMP pictures |
| imageaffine() | Returns the image after affine transformation |
| imageaffinematrixconcat() | Concatenate two matrices |
| imageaffinematrixget() | Get matrix |
| imagealphablending() | Set the color blending mode of an image |
| imageantialias() | Whether to use antialiasing (antialias) function |
| imagearc() | Draw elliptical arc |
| imagechar() | Write horizontal characters |
| imagecharup() | Draw a character vertically |
| imagecolorallocate() | Assign a color to an image |
| imagecolorallocatealpha() | Assign color and transparency to an image |
| imagecolorat() | Get the color index value of a pixel |
| imagecolorclosest() | Gets the index value of the color closest to the specified color |
| imagecolorclosestalpha() | Gets the index of the color closest to the specified color plus transparency |
| imagecolorclosesthwb() | Gets the index of the black and white color closest to the specified color |
| imagesx(), imagesy() | Get image width and height |
To use PHP image processing functions, you need to load the GD support library. Please make sure php.ini loads the GD library:
On Windows server:
extension=php_gd2.dll
On Linux and Mac systems:
extension=php_gd2.so
Use the gd_info() function to view information about the currently installed GD library:
<?phpvar_dump(gd_info());?>
The output is roughly as follows:
array(12) { ["GD Version"]=> string(26) "bundled (2.1.0 compatible)" ["FreeType Support"]=> bool(true) ["FreeType Linkage"]=> string(13) "with freetype" ["T1Lib Support"]=> bool(false) ["GIF Read Support"]=> bool(true) ["GIF Create Support"]=> bool(true) ["JPEG Support"]=> bool(true) ["PNG Support"]=> bool(true) ["WBMP Support"]=> bool(true) ["XPM Support"]=> bool(false) [" XBM Support"]=> bool(true) ["JIS-mapped Japanese Font Support"]=> bool(false)}