Abstract: An encoder-decoder for processing entropy encoded data. The encoder-decoder provides a bitstream buffer for receiving variable length code words that are extracted from fixed length data words received and stored in a register. Variable length words are loaded into the bitstream buffer until all bits are loaded with data, at which time data is read out of the bitstream register and it is cleared and ready for new data. During decoding, the bitstream buffer receives a fixed length data word that is made up of multiple variable length code words. These code words are individually read out and read into a fixed length register. The contents of the fixed length register are then read out for further processing by a connected system. A controller is provided for coordinating and controlling encoding and decoding operation.

Abstract: A segmented photosensor array for an image scanner has segments with imperfect alignment. During scanner manufacturing, photosensor segment alignment data, such as segment position offset and segment angle, is measured. The offset and angle are stored in non-volatile memory within the scanner. A position correction system uses the stored alignment data to correct position and angle values before being processed by a rectification system. Most pixels require simple geometry calculations. However, a more complex state machine is needed to handle the transition from one photosensor segment to the next. Correcting for segment position offset and angle errors enables a cost reduction for the sensor array and, in particular, reduces costs associated with scrap.

Abstract: In an image scanner, rectification of sensor data is computed in real time, so that sensor data do not need to be stored into an image memory. As a result, performance is improved because firmware for sensor data storage and retrieval is eliminated, and fewer devices are arbitrating for access to the image memory. The rectification system is extendable to color scanning by providing one rectification module for each color. In various example embodiments, sensor data are entered into a data buffer configured as a first-in-first-out buffer. The buffer is sufficiently long to hold a little more than one scan-line of data. In a first example embodiment, an interpolator module receives sensor data from fixed locations within the buffer. As new values are entered, old unneeded values are simply discarded. Some special conditions require a distinctive (for example, blank or null) value to be inserted to maintain proper data alignment within the buffer.