US 4,342,051 AGranted

Method of and system for reproducing or transmitting half-tone images

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsKazufumi Suzuki, Shumi Kumagai, Yuetsu Ochiai, Akira Mizoguchi

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Abstract

An original image field is successively scanned along each of parallel line paths to detect the image density of the scanned elemental picture area. A plurality of recurring sequences of binary digits or pulses is generated for each of the scanned line paths in synchronism with the scansion of each elemental picture area, thereby forming dot pattern conversion matrices corresponding in number to the number of discrete gradation steps or image densities with the pulses representing the dots in each matrix. The detected image density is used to select a corresponding one of the dot pattern matrices to represent the scanned area with a dot if the latter is present in a specified position in the corresponding matrix by allowing the selected recurring pulse sequence to be delivered to a recording unit which is moved with respect to a recording field in synchronism with the scansion of the original field.

Claims6

Dependent claims

A signal conversion circuit comprising:

first means for scanning an image field along each of a plurality of parallel line paths of elemental picture areas to detect the image density of each of the scanned elemental areas, a predetermined number of said elemental areas being arranged in rows and columns forming an image field matrix;
second means for selecting a corresponding digital pattern from among a plurality of digital patterns according to the detected image density, each of said digital patterns being composed of a conversion dot matrix having digital values of "1"s and "0"s in a predetermined number and arrangement corresponding to the detected image density, the total number of "1"s and "0"s in said conversion dot matrix being equal to the total number of elemental areas in the corresponding image field matrix;
and
third means for detecting the presence of a "1" or "0" in the selected digital pattern in a location corresponding to the location of said elemental area in said image field matrix to represent said elemental area by a "1" in a recording field in response to the detection of said "1" or by a "0" in said recording field in response to the detection of said "0", wherein said second and third means comprise:
means for generating a plurality of recurring sequences of binary digits for each said scanned line paths, said binary digits in each of the recurring sequences being shifted in their relative positions in response to the scanning of each elemental area;
and
means for detecting the presence of a said binary digit in one of said recurring sequences in a response to said detected image density to represent the scanned elemental area with said detected binary digit.

4 more elements

A signal conversion circuit comprising:

first means for scanning an image field along each of a plurality of parallel line paths of elemental picture areas to detect the image density of each of the scanned elemental areas, a predetermined number of said elemental areas being arranged in rows and columns forming an image field matrix;
second means for selecting a corresponding digital pattern from among a plurality of digital patterns according to the detected image density, each of said digital patterns being composed of a conversion dot matrix having digital values of "1"s and "0"s in a predetermined number and arrangement corresponding to the detected image density, the total number of "1"s and "0"s in said conversion dot matrix being equal to the total number of elemental areas in the corresponding image field matrix;
and
third means for detecting the presence of a "1" or "0" in the selected digital pattern in a location corresponding to the location of said elemental area in said image field matrix to represent said elemental area by a "1" in a recording field in response to the detection of said "1" or by a "0" in said recording field in response to the detection of said "0", further comprising:
means for detecting the average value of said detected image densities of previously scanned elemental picture areas;
means for detecting the average value of the digital values which represent said previously scanned elemental picture areas;
means for detecting the difference between said average values;
and
means for adding said difference value to the detected image density of a subsequently scanned elemental picture area.

6 more elements

Dependencies are inferred from the claim text.