PHP best way to check if file is an image

The getimagesize function of php provides lot of information about an image file , including its type. The type can be used to check if the file is a valid image file or not.

To check if a file is an image or not, use the function

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function is_image($path) {     $a = getimagesize($path);     $image_type = $a[2];           if(in_array($image_type , array(IMAGETYPE_GIF , IMAGETYPE_JPEG ,IMAGETYPE_PNG , IMAGETYPE_BMP)))     {         return true;     }     return false; }

$a[0] and $a[1] are the width and height of the image.
$a[2] has the image type.

Other image formats include :

[IMAGETYPE_GIF] => 1
[IMAGETYPE_JPEG] => 2
[IMAGETYPE_PNG] => 3
[IMAGETYPE_SWF] => 4
[IMAGETYPE_PSD] => 5
[IMAGETYPE_BMP] => 6
[IMAGETYPE_TIFF_II] => 7
[IMAGETYPE_TIFF_MM] => 8
[IMAGETYPE_JPC] => 9
[IMAGETYPE_JP2] => 10
[IMAGETYPE_JPX] => 11
[IMAGETYPE_JB2] => 12
[IMAGETYPE_SWC] => 13
[IMAGETYPE_IFF] => 14
[IMAGETYPE_WBMP] => 15
[IMAGETYPE_JPEG2000] => 9
[IMAGETYPE_XBM] => 16
[IMAGETYPE_ICO] => 17
[IMAGETYPE_UNKNOWN] => 0
[IMAGETYPE_COUNT] => 18

Note :

1. mpeg videos are detected as IMAGETYPE_ICO !!