[TYPO3-english] resize image in a text-pic content

[TSniper]

Hello,

I want to resize a text-pic content element, but i didn't found how can i resize he image.
When i inspect the image i found that the width = 300
here the html :
<img src="fileadmin/_processed_/csm_gartenzaun_011_f9794b6d2b.jpg" width="300" height="165" alt="">
i attached an screen for what i want to do.

Thank you for any help