Optimal image-quality selection apparatus

• US 4,888,646 A
• Filed: 01/25/1989
• Issued: 12/19/1989
• Est. Priority Date: 01/29/1988
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Sugiura, Fumihiko, Umeda, Tetsuo
• Primary Examiner(s): COLES, EDWARD L
• Application Number:
  US07/301,853
• Time in Patent Office: 328 Days
• Field of Search: 358/256, 358/280, 358/284, 358/282, 358/293, 358/283, 382/9
• US Class Current: 358/464
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/162 Quantising the image signal

Abstract

An optimal image-quality selection apparatus calculates a ratio of the number of graphic blocks having a predetermined size to the number of all graphic blocks of an image having two or more depth levels of color and selects an image having a largest one of the ratios as an image of optimal quality.

Claims

1. An optimal image-quality selection apparatus comprising:

means for quantizing a signal representing an image, obtained from a scanner, to output two or more video signals representing the image by different depth levels;

means for detecting and counting all the graphic blocks included in each of the two or more video signals, the graphic block being defined as a chain of dots in the image;

means for detecting and counting the number of graphic blocks having a predetermined size in each of the two or more video signals;

means for calculating a ratio of the number of graphic blocks having the predetermined size to the number of the all graphic blocks included in each of the two or more video signals, respectively; and

means for selecting a largest one out of the ratios corresponding to the two or more video signals to output a signal representing that a depth level corresponding to the largest ratio is optimal.

2. An optimal image-quality selection apparatus comprising:

means for quantizing a signal output from a scanner into a plurality of video signals having different depth levels of a color;

a plurality of block extractors for inputting the plurality of the video signals to extract graphic blocks, respectively;

a plurality of pairs of first and second counters connected to said block extractors in one to one correspondence, said first counter counting number of all the graphic blocks and said second counter counting number of graphic blocks having a predetermined size;

a plurality of dividers each connected to said a plurality of pairs of said first and second counters in one to one correspondence, each of the plurality of said dividers calculates a ratio of the number of graphic blocks having a predetermined size and the number of all the graphic blocks output from each of the corresponding pairs; and

a comparator for comparing the ratios output from the plurality of said dividers to select a largest ratio and outputting a signal representing that an image having the largest ratio has an optimal image quality.