Google announced a change to the Ad Review Center in AdSense to help users find and review ads more efficiently.
On the Inside AdSense blog, Google's Marcel Crasmaru explains, "Using the technology behind Google Image Search, you’ll now be able to upload an image file from your computer to search for related image ads; you can then review and take action on the returned ads."
"For example, you might want to find and block ads that contain the logo of a competitor," says Crasmaru. "After you upload and search for the logo, we’ll return image ads that contain the logo and which are eligible to appear on your pages. Please note that you can upload images with a maximum file size of 2MB and a largest dimension of 1024 pixels. To try this feature, log in to your AdSense account and visit the ‘Allow and block ads’ tab."
Google suggests using filters sparingly - specifically when you prefer not to have a particular ad or advertiser appear on your pages.