Abstract: A digital scan converter with an initialization circuit. The initialization circuit, for example, a dedicated circuit or a computer, relates each pixel in a converted image to two or more respective pixels which lie adjacent to it and which are selected from an original image which is generated by a scanner. The initialization circuit also calculates and makes available interpolation constants to be used in deriving the value of a given pixel in terms of its respective, adjacently lying, group of pixels. When the converted image has a raster scan format, a satisfactory image is obtained when the respective group of pixels consists of two pixels between which lies the pixel whose value is to be calculated. By predefining the relationship between the pixels in the converted and original images before actual conversion begins real time operation is achieved.

Abstract: A portable cardiac monitor analyzes the PQ and ST portions of an electrocardiogram waveform and establishes a "normal" or standard ST ratio deviation of the difference between the ST and PQ levels. When a subsequently measured ST ratio deviation exceeds the previously stored normal value, an alarm is indicated indicating a possible ischemic condition. The pulse rate may also be monitored to provide an alarm whenever the pulse rate rises above or falls below a predetermined value.