Abstract: A method and apparatus in which regions of a web image containing textual information (text-containing regions) and regions of the image not containing textual information (non-text-containing regions) are identified and differentially transcoded so as to provide an image quality for the text-containing regions which is superior to (i.e., less degraded relative to) the image quality of the non-text-containing regions. A data structure is generated based on the web image, the data structure containing at least one coded representation for each of the text-containing regions and a plurality of coded representations of each of the non-text-coniaining regions. A coding of the web image is generated from the data structure by selecting coded representations based on characteristics of a particular target client device and the bandwidth of a communications channel. Various coded representations may be generated by down-sampling the given region, or reducing the color depth or number of gray levels thereof.

Abstract: E-mail which may be infected by a computer virus is advantageously filtered by incorporating a “Reverse Turing Test” to verify that the source of a potentially infected e-mail is human and not a machine, and that the message was intentionally transmitted by the apparent sender. Such a test may, for example, involve asking a question which will be easy for a human to answer correctly but quite difficult for a machine to do so. The e-mail may be deemed to be potentially infected based on an analysis of executable code which is attached to the e-mail, or merely based on the fact that executable code is attached. The e-mail may also be deemed to be potentially infected based on additional factors, such as, for example, the identity of the sender and past experiences therewith. Spam E-mail may also be advantageously filtered together with virus-containing e-mail with use of a single common filtering system.