Image segmentation method and device

Claim 1

A method of distinguishing character and photograph areas on a document, in which method a series of image signals obtained by pho­toelectrically scanning a document line by line and each image signal corresponding to the optical density information of an image dot on the document, is fed to a segmentation device in which character and photograph areas are distinguished from one another, characterised in that before being fed to the segmentation device (42) the series of image signals is divided up into a number of groups, there being determined for each group one new image signal corresponding to the average of the image signals in that group.

Claim 2

A method of distinguishing character and photograph areas on a document, in which method a series of image signals obtained by pho­toelectrically scanning a document line by line and each image signal corresponding to the optical density information of an image dot on the document, is fed to a segmentation device in which character and photograph areas are distinguished from one another, characterised in that before being fed to the segmentation device (42) the series of image signals is divided up into a number of groups, there being determined for each group one new image signal corresponding to the average of the image signals in that group.

Claim 10

A method of distinguishing character and photograph areas on a document in a scanning, processing and recording device, comprising the following steps: a) photoelectric scanning (11) of character and photograph areas on an original document (10), b) storage of the digital image signals obtained from the scan in a scan bit map memory (12), c) conversion of these digital image signals by means of a raster con­version process (14) to a rastered image and storage thereof in a raster bit map memory (16), d) conversion of the digital image signals by means of a threshold con­version process (13) to a thresholded image and storage thereof in a threshold bit map memory (15), e) subjecting the digital image signals to an analysis process (19) in which, by means of a segmentation process (24), the photograph areas and the character areas are distinguished from one another and in which a switching signal is stored in a switching memory (25) on each transition between these areas, f) reading out of the rastered image stored in the raster bit map memory (16) and of the threshold image stored in the threshold bit map memory (15) in synchronization with reading out of the switching signals stored in the switching memory (25), part of the rastered image or a part of the thresholded image being fed each time to a printing device in dependence on the switching signal, characterised in that the analysis process (19) comprises a reduc­tion process (20) in which a group of digital image signals is com­bined each time to form a new digital image signal that corresponds to the average of the image signals of that group and subsequently is subjected to the segmentation process (24).

Claim 11

A method of distinguishing character and photograph areas on a document in a scanning, processing and recording device, comprising the following steps: a) photoelectric scanning (11) of character and photograph areas on an original document (10), b) storage of the digital image signals obtained from the scan in a scan bit map memory (12), c) conversion of these digital image signals by means of a raster con­version process (14) to a rastered image and storage thereof in a raster bit map memory (16), d) conversion of the digital image signals by means of a threshold con­version process (13) to a thresholded image and storage thereof in a threshold bit map memory (15), e) subjecting the digital image signals to an analysis process (19) in which, by means of a segmentation process (24), the photograph areas and the character areas are distinguished from one another and in which a switching signal is stored in a switching memory (25) on each transition between these areas, f) reading out of the rastered image stored in the raster bit map memory (16) and of the threshold image stored in the threshold bit map memory (15) in synchronization with reading out of the switching signals stored in the switching memory (25), part of the rastered image or a part of the thresholded image being fed each time to a printing device in dependence on the switching signal, characterised in that the analysis process (19) comprises a reduc­tion process (20) in which a group of digital image signals is com­bined each time to form a new digital image signal that corresponds to the average of the image signals of that group and subsequently is subjected to the segmentation process (24).