Question

I need to know whether I can trust this code to get the image format:

$image = new Imagick($path);
$format = $image->getImageFormat();

Or should I still check extension, mime type, etc like usual?

Answer 1

You can trust it much more than just checking the extension of the file (pic.jpg for example) with simple php string functions.

You can have an experiment. Rename a .jpg image file so that it becomes .png, for example. Use simple tools of the Windows “Rename”. So it seems now that the image is a .png image.
But try Imagick in cmd with -verbose command, like this:

C:\>identify -verbose pic.png
Image: pic.png
  Format: JPEG (Joint Photographic Experts Group JFIF format)
  Class: DirectClass
  Geometry: 482x362+0+0
  Resolution: 72x72
  ... many more here ...

And you will see that in reality the image is .jpg. The same is with your $image->getImageFormat(); somewhere in your program.

Imagick is powerful tool. Unfortunately there is much less information about its API in PHP than GD has.