The image quality of photographic and digitized images is determined by their sharpness, graininess, tone reproduction and color reproduction characteristics. Various criteria have been suggested to evaluate these properties. In this paper, color reproduction characteristics of endoscopic images is mainly described. A method of color reproduction for news paper printing from television picture is also described.
An experiment on the median interpolation for the non-interlace conversion has been made. The most TV manufacturers in Japan have introduced the motion adaptive interpolation method for the non-interlace conversion in their IDTVs or EDTVs. At this moment, we have made the experiment to grasp the performance of the median interpolation using the median filter as compared with other interpolation methods. As a result, it is confirmed that the median interpolation can be used sufficiently from the total view of the picture quality and the circuit scale.
A codec for photographic image transmission is developed 2-dilensional Discrete Cosine Transform(DCT), scalar quantization, and Huffman coding are applied to the codec. A code table for significant coefficient levels is selectecd from plural tables according to statistical characteristic of an input image. 1/8 is achieved for monochrome photographic A conpression ratio of 1/4 -images with keeping sufficient decoded image quality.
Vector quantization(VQ) has proven to be an efficient technique for commpression of a sampled image at under 1.0 bpp. VQs in the pixel domain can be defined as a kind of pattern-matching coder which replaces a pixel subblock by some matching pattern. In the VQ, the pattern set(codebook), a collection of possible matching patterns, is generated from training images in advance. If the statistical properties of compressed image and training images are not matched, the problem of pattern-set mismatch occurs and excess quantization error results. To solve this problem, this paper develops a novel universal pattern-matching scheme, named PMC for short,which has the power of self-organizing its own pattern-set and which basically escapes the pattern-set mismatch.
For high-speed decoding of the MMR code, presented is a new pipelined CODEC, which generates output image nearly at the maximum data flow rate of I byte per machine cycle. A pipeline hazard which is intrinsic to the MMR coding scheme is identified. Proposed pipeline configuration optimized for the MMR-decoding, enhanced parallelism to generate - a fixed amount of the image regardless the word-boundary, and hardwired controls for key-steps are attributed for this high data rate. This was designed as a VLSI, fablicated and evaluated. Any of the CCITT test charts was expanded in less than 0.15 sec. with machine cycle time of 200ns.