Читать книгу Rethinking Prototyping - Группа авторов - Страница 128

The search for How to say more with less? starts early with the development of big distance speech transmission such as telegraphs. Bandwidth was limited and expensive long before that name existed. Therefore, it was important to condense content to its essence consisting of as few symbols as possible, as many as necessary. A lot of different strategies where developed in information theory – a term also coined only when that branch already was in its first period of prosperity. Systems where developed not only by Claude Elwood Shannon, whose paper A Mathematical Theory of Communication (Shannon and Weaver 1949) gave that branch its name but also by predecessors like Morse, Hartley or Nyquist (Gleick 2011). These strategies are not only employed when transmitting but also when storing information in as few storage as possible, for example in image compression. Two widely known techniques are the Graphics Interchange Format (GIF) and the format developed by the Joint Photographic Expert Group (JPEG). GIF reduces the number of allowed colours to a limited precise set of e.g. 256 colours and a matrix of indexes, where which colour is placed. JPEG on the other hand splits up the image in 8 x 8 pixel blocks and applies a discrete cosine transformation (DCT), a procedure very similar to the Fourier transformation described in this paper. Both, GIF and JPEG are so-called lossy-compression methods that try to discard neglectable parts (such as the high frequencies in JPEG). Both methods – and any other method of compression or more generally formulated: abstraction – are only a certain view on things. In addition, because they are views, they pose a certain filter to the data and in turn, produce their own artifacts. Therefore, they all qualify best for some uses while being unserviceable for others. The method described fits well for wood. But it also represents a specific model, who’s encryption has been negotiated and tested and must be known to the receiver in order to be able to decrypt. This can be overcome by having the computer learn this over time as well.