phpThumb 可以幫你做縮圖

bestlong

PHP thumbnail generator. Optional resizing, cropping, watermarking, unsharp mask sharpening, rotating, caching, borders. GIF reading with/without GD support. EXIF thumbnails can be extracted and/or used for large-source support. Works with any GD version.

支援讀取的圖片格式:
JPEG (via GD or ImageMagick)
PNG (via GD or ImageMagick)
GIF (via GD, ImageMagick, or phpthumb.gif.php)
BMP (via ImageMagick or phpthumb.bmp.php)
any image format ImageMagick can read

支援輸出的格式:
JPEG (via GD or ImageMagick)
PNG (via GD or ImageMagick)
GIF (via GD or ImageMagick)
BMP (via ImageMagick or phpthumb.bmp.php)
ICO (via ImageMagick or phpthumb.ico.php)

http://sourceforge.net/projects/phpthumb/
http://phpthumb.sourceforge.net/