You can change the picture categories MyAdBlock draws from in MyAdBlock's options.

1. Click the AdBlock button in the browser toolbar and select MyAdBlock.

The AdBlock menu showing MyAdBlock is active and which picture categories are selected

2. Click the toggle button next to a category to change whether it is selected (green) or not (gray).

Changing your selected picture categories in MyAdBlock's options

Deselecting all the categories turns off MyAdBlock.

Your selections are saved automatically. Just close the options page when you're done.