An example system disclosed herein comprises a web browser monitor to extract textual information from a captured image comprising at least a portion of content displayed by a web browser implemented by a monitored device, and determine color scheme information for a region of the captured image comprising at least a portion of the content displayed by the web browser. The example system also comprises a central processing facility to process the extracted textual information received from the web browser monitor, and compare the color scheme information received from the web browser monitor to reference color schemes associated with reference web pages to determine web sites accessed using the web browser.