[TYPO3] Crop images for gallery with t3lib_stdgraphics function crop(&img, $conf)

[Kahlil Lechelt]

Hi,

i am currently working on a gallery extension for a project and i need 
to crop thumbnails to a specific size.
I would like to use the crop()-function in t3lib_stdgraphic for that but 
i am not rally sure how to use it.
What is going into the $conf-Variable?
Can somebody post me a quick how to? Or does anybody have a tip where i 
can find an example or something?

Best regards,
Kahlil