Pattern preliminary processing system
First Claim
1. A pattern preliminary processing system comprising filtering means for filtering pattern signals by means of a mask, the weight of the respective regions on the mask being nearly symmetrical with respect to the center of the mask and the total weight of all regions of the mask being nearly zero so as to emphasize the variations in shade along the boundary between the pattern and background, first bi-valuing means for dividing the output of said filtering means into two values at a first threshold level, second bi-valuing means for dividing the output of said filtering means into two values at a second threshold level lower than said first threshold level, and means for classifying pattern signals between said first and second threshold levels into a first state and a second state by reference to the signal level of small regions adjacent to the regions corresponding to said pattern signals, said first state including signals above said first threshold level, said second state including signals under said second threshold level.
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Abstract
A pattern preliminary processing system wherein high and low frequency noise other than the pattern signal from a pick-up tube are eliminated by a filtering circuit thereby to "relieve" the pattern against the background and the thus obtained pattern signal is tri-valued into signals of high, medium and low levels by means of a processing circuit having two different threshold values, and then the signal of the medium level is converted into a signal of high or low level with reference to peripheral information thereby to finally bi-value the pattern signal.
72 Citations
8 Claims
- 1. A pattern preliminary processing system comprising filtering means for filtering pattern signals by means of a mask, the weight of the respective regions on the mask being nearly symmetrical with respect to the center of the mask and the total weight of all regions of the mask being nearly zero so as to emphasize the variations in shade along the boundary between the pattern and background, first bi-valuing means for dividing the output of said filtering means into two values at a first threshold level, second bi-valuing means for dividing the output of said filtering means into two values at a second threshold level lower than said first threshold level, and means for classifying pattern signals between said first and second threshold levels into a first state and a second state by reference to the signal level of small regions adjacent to the regions corresponding to said pattern signals, said first state including signals above said first threshold level, said second state including signals under said second threshold level.
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6. A pattern preliminary processing system comprising:
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filtering means including a first register group for storing pattern input signals, a second register group for storing information of the weight of a mask, a circuit for multiplying the contents of said first register group by the corresponding contents of said second register group, and a circuit for adding the outputs of said multiplying circuit, so as to emphasize the variations in shade along the boundary between the pattern and background; first bi-valuing means for dividing the output of said filtering means into two values at a first threshold level; second bi-valuing means for dividing the output of said filtering means into two values at a second threshold level lower than said first threshold level; and means for classifying pattern signals between said first and second threshold levels into a first state and a second state by reference to the signal level of small regions adjacent to the regions corresponding to said pattern signals, said first state including signals above said first threshold level, said second state including signals under said second threshold level. - View Dependent Claims (7, 8)
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Specification