Image processing for electronic document storage

Reos is a document image processing system which stores images of paper documents as a bit map on optical discs. These images are displayed on a CRT at a lower resolution compared to the stored data. The conversion and display of the stored information must be performed quickly to achieve an acceptable system response time; since even highly optimised software could not process more than a few thousand pixels per second, a hardware solution capable of processing many millions of pixels per second was developed. The mesh offset algorithm which combines image resampling with convolution, was selected for its performance and ease of mapping onto silicon. The hardware of this algorithm option is suitable for more general purposes image processing tasks such as filtering to reduce noise, or contrast enhancement. A high level description of the system has been mapped onto silicon using a number of design options to provide the best balance between speed of design, performance and die area. The resolution converter in 2.5 mu m CMOS double layer metal technology supports scan path test and signature analysis for production test purposes.