Using the Product > Web Blocking :
I am unable to see pictures on an allowed website.
If the images on a website are showing as blank images with a red 'x' in them, check the properties of the image (Right click on it and select properties) and see where the source of the image is. Occasionally, images on a website are pulled from a different domain than the actual website so they can sometimes be blocked while the site itself is allowed.
For example, you might be visiting www.website.com, while the pictures on the site are coming from images.website.com. These are two different domains (websites), even though they are for the same page.
Check the categorization of the domain that the images are coming from and if it is a category that you have selected to be banned you can create a site override for that domain. This will enable pictures to display properly.