Abstract: A thermal dye printer media element for use in a thermal printer includes sequential color patches which form multiple color groups located along a length of the element. Metering marks are provided repetitively along the length of the element for measurement of distances along the element. The spacing between successive pairs of the metering marks may be uniform, change in a linear fashion, or change in a nonlinear fashion. The metering marks may be optically or magnetically detectable. The first and second metering mark sequences may be essentially the same. Alternatively, the first and second metering mark sub-sequences may be different. The start of a metering mark sequence may be aligned with an edge of a color patch, or may be offset from an edge of a color patch. A third sequence of metering marks may be provided for a third color patch, wherein said third metering mark sequence is different from said first sequence.

Abstract: A method of calibrating optical sensors for a thermal printer (10) is disclosed. A thermal printer for printing color images which uses a dye donor web having a repeating series of spaced frames of yellow, magenta and cyan colored heat transferable dyes, apparatus for identifying the different color frames of each series uses a source of second light and a source of first light. The apparatus responds to the intensity of second and first source light which passes through a dye donor frame to identify that dye donor frame. A CPU adjusts a digital potentiometer attached to a photodetector to determine a series of values for a first dye donor frame. The procedure is repeated for a second series of values for a second dye donor frame. An absolute value of the different potentiometer values for the two dye donor frames is determined, and the CPU adjusts the potentiometer setting to the maximum value determined.

Abstract: A video transceiver includes a compressor which grabs a pair of blocks of image data from a video frame store and loads them into a dual port memory. A first processor, working through one of the dual ports, performs a portion of an image compression algorithm, while a second processor, working through a second one of the dual ports, performs the remainder of the compression algorithm on each one of the two pairs of blocks, both processors operating in parallel to speed up the entire process. A key word in each block is changed in accordance with each step, so that each of the two processors is prevented from grabbing the wrong one of the two blocks from the dual port memory. The resulting compressed data is queued in a temporary buffer, from which it is returned to another portion of the video frame store in serial fashion, rather than block, in preparation for serial transmission.