# US 5,351,138 A · Image area discriminating device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,351,138 A - Document ID: US5351138A - Status: Granted - Kind: A - Application number: 07/688,930 - Filed: 1991-04-23 - Granted: 1994-09-27 - Earliest claimed: 1990-04-24 - Assignees: Ricoh Company, Ltd. - Inventors: Tomio Sasaki; Shinji Kobayashi; Masahito Obata - Web page: https://patentgrep.com/patent/US5351138A ## CPC - H04N 1/40075: {Descreening, i.e. converting a halftone signal into a corresponding continuous-tone signal; Rescreening, i.e. combined descreening and halftoning} - H04N 1/40062: {Discrimination between different image types, e.g. two-tone, continuous tone} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image area dicriminating device for a digital copier, facsimile machine, scanner or similar imaging equipment. The device determines whether areas constituting an input image each has undergone dot processing or not automatically. ## Claims ### Claim 1 A device for discriminating an image area, comprising: a) MTF (Modulation Transfer Function) correcting means for executing MTF correction with input image data; and b) record dot and non-record dot detecting means including: 1) means for receiving an MTF corrected image signal outputted by said MTF correcting means as input image data; 2) means for comparing (1) a bi-dimensional pattern of said input image data with (2) a predetermined detection pattern, so as to detect a record dot and a non-record dot; and 3) means for producing a result of comparison. ### Claim 2 (depends on 1) A device as claimed in claim 1, further comprising: destiny difference detecting means for determining whether or not a difference between (1) density data of a pixel of interest included in said input image data and (2) density data of pixels which surround said pixel of interest, is greater than a predetermined value. ### Claim 3 (depends on 1) A device as claimed in claim 1, further comprising: density detecting means for determining that, among pixels corresponding to a pixel of interest included in said input image data, (1) a pixel having a high density or (2) a pixel having a low density, is the pixel of interest; and density difference detecting means for determining whether or not a difference between (1) density data output by said density detecting means and (2) density data of pixels which surround said pixel of interest, is greater than a predetermined value. ### Claim 4 (depends on 1) A device as claimed in claim 1, wherein: the device further comprises density difference detecting means for determining whether or not a difference between (1) density data of a pixel of interest included in said input image data and (2) density data of pixels which surround said pixel of interest, is greater than a plurality of predetermined values; and the device comprises a plurality of said record dot and non-record dot detecting means. ### Claim 5 (depends on 1) A device as claimed in claim 1, further comprising: averaging means for averaging said input image density data in a first bi-dimensional arrangement; selecting means for selecting a plurality of predetermined values in response to an output of said averaging means; and density difference detecting means for determining whether or not a difference between (1) density data of a pixel of interest included in said input image data and (2) density data of pixels which surround said pixel of interest, is greater than a predetermined value; wherein said record dot and non-record dot detecting means includes means for comparing (1) a second bi-dimensional arrangement of an output of said density difference detecting means with (2) a predetermined record dot and non-record dot detection pattern. ### Claim 6 (depends on 1) A device as claimed in claim 1, wherein: a) said device comprises means for determining whether or not each area of said input image information has undergone dot processing; and b) said record dot and non-record dot detecting means includes: 1) means for determining the number of patterns in which said bi-dimensional pattern and said record dot and non-record dot detection pattern match; and 2) means for determining whether or not said number of patterns is greater than a predetermined number. ### Claim 7 (depends on 1) A device as claimed in claim 1, further comprising: a) a plurality of density difference detecting means, each constituting means for determining whether or not a difference between (1) density data of a pixel of interest included in said input image data and (2) density data of pixels surrounding said pixel of interest, is greater than a predetermined value; b) selecting means for selecting output signals of said plurality of density detecting means at predetermined timings, wherein said record dot and non-record dot detecting means includes: 1) means for comparing (1) a bi-dimensional pattern of said signals selected by said selecting means with (2) a predetermined record dot and non-record dot detection pattern; and 2) means for producing a result of comparison; and c) dot pattern identifying means, responsive to an output of said record dot and non-record dot detecting means, for determining whether or not said input image data is representative of a dot pattern. ### Claim 8 (depends on 1) A device as claimed in claim 1, further comprising: a plurality of density difference detecting means, each constituting means for determining whether or not a difference between (1) density data of a pixel of interest included in said input image data and (2) density data of pixels surrounding said pixel of interest, is greater than a reference value which varies with a position of said bi-dimensional pattern. ### Claim 9 A device for discriminating an image area, comprising: image reading means for dividing a document image into a number of small pixel areas, for reading image density of each of said image areas, and for outputting an electric signal associated with said image density; first subscan magnification changing means for driving the document and said image reading means relative to each other for scanning said document, and for adjusting, in response to a designated magnification change ratio, a scanning speed so as to change a magnification change ratio in a subscanning direction; converting means for converting an analog signal output by said image reading means to a digital signal; main-scan magnification changing means for changing, in response to a designated magnification change ratio, a magnification change ratio by thinning or interpolating said digital signal output by said converting means in a main scanning direction; record dot and non-record dot detecting means for comparing a bi-dimensional pattern of said digital signal with a predetermined record dot and non-record dot detection pattern, and for outputting a result of comparison; and second subscan magnification changing means for thinning or interpolating image data output by said first subscan magnification changing means on the basis of a designated magnification change ratio. ### Claim 10 A device for discriminating an image area, comprising: image reading means for dividing a document image into a number of small pixel areas, for reading image density of each of said image areas, and for outputting an electric signal associated with said image density; subscan magnification changing means for driving the document and said image reading means relative to each other so as to scan said document, and for adjusting, in response to a designated magnification change ratio, a scanning speed so as to change a magnification change ratio in a subscanning direction; converting means for converting an analog signal output by said image reading means to a digital signal; main-scan magnification changing means for changing, in response to a designated magnification change ratio, a magnification change ratio by thinning or interpolating said digital signal output by said converting means in a main scanning direction; and record dot and non-record dot detecting means for comparing a bi-dimensional pattern of said digital signal with a predetermined record dot and non-record dot detection pattern, and for outputting a result of comparison.