Abstract: In an image reading device for reading an original image, an original image is picked up and converted into two-dimensional positional image data represented in a two-dimensional positional coordinate system. The two-dimensional positional image data is further converted into two-dimensional spatial frequency image data represented in a two-dimensional spatial frequency coordinate system, and then into high frequency image data and low frequency image data. The high frequency image data is subjected to moire component selecting and depressing operations to correct the high frequency image data whose moire components are depressed, and then the low frequency image data and the corrected high frequency image data are reconverted into corrected two-dimensional positional image data, thereby reproducing the original image with no moire.

Abstract: A mutant of an extracellular enzyme-producing microorganism belonging to genus Bacillus, which is resistant to a cell membrane synthesis inhibitor, including vancomycin and ristocetin, is disclosed. The cell membrane synthesis inhibitor-resistant mutant can produce such an enzyme as cellulase, protease, or amylase about 2 to 4 times of the parent strain. Such a mutant can be produced by subjecting an extracellular enzyme-producing microorganism tot a mutation treatment, and culturing said microorganism in a culture medium containing a cell membrane synthesis inhibitor.

Abstract: A system for converting an analog video signal obtained by scanning an original image to be processed into a two-valued video signal such as an input portion of a facsimile machine includes a peak/valley extracting circuit for extracting peaks and valleys in the analog video signal before thresholding the analog video signal so as to determine an optimal threshold level to be used in thresholding. The peak/valley extracting circuit includes peak and valley thresholds in addition to the threshold to be used in thresholding the analog video signal to produce a two-valued video signal. The peak/valley extracting circuit is so structured to supply a peak/valley extraction signal if an extracted peak or valley also satisfies the condition that it is equal to or higher or lower in level than the peak or valley threshold.

Abstract: A system for converting an analog image signal into a digital image signal is provided. The system comprises an analog-to-digital signal converter for producing a digital signal by subjecting an incoming analog signal to threshold processing with a threshold level. The system also comprises a peak/valley extracting circuit for extracting peak and valley points corresponding to thin lines and narrow gaps between lines, respectively, in the original image scanned. The extracted peak and valley points are utilized in the analog-to-digital conversion processing so as not to lose information as to thin lines and narrow gaps between lines. Especially, in extracting peak and valley points, the concentration or level of a particular picture element is compared with that of the adjacent picture elements at least in two directions.