1. One or more computer-readable storage memories for use at a computer system, the one or more computer-readable storage memories embodying processor-executable instructions which, responsive to execution by at least one processor, are configured to: cause the computer system to: receive a compressed image associated with a webpage, the compressed image comprising a plurality of pixels associated with an image taken from a frame buffer of a computing device, wherein a first portion of the compressed image has less compression than a second portion of the compressed image; decompress the compressed image into a decompressed image by using a decompression algorithm on the compressed image; output a rendered image associated with the decompressed image in a user interface; obtain, directly from a website that originated the webpage, the webpage; output an image of the directly obtained webpage; analyze the rendered image and the image of the directly obtained webpage to identify one or more differences between the rendered image and the image of the directly obtained webpage; and indicate, in the user interface, the one or more differences.