Pattern preliminary processing system
Analog-digital converter with variable threshold levels Patent #: 4064484
ApplicationNo. 05/960541 filed on 11/14/1978
US Classes:375/240.24, Block coding382/270Variable threshold, gain, or slice level
ExaminersPrimary: Britton, Howard W.
Assistant: Coles, Edward L.
Attorney, Agent or Firm
International ClassH04N 7/26 (20060101)
Foreign Application Priority Data1978-01-24 JP
AbstractA frame of a gray-scaled picture is divided into blocks, in each of which the mean luminance of picture elements is used as a threshold value for comparison with each picture element signal to classify it into 0 or 1 according to its magnitude to provide a resolution component. From the resolution component and each picture element signal in the block are calculated two gray components; the resolution component and the two gray components are used as coded outputs for each block. The size of each block is changed in accordance with the property of the picture in the portion corresponding to the block.