| 摘要 |
PURPOSE:To remove an afterimage phenomenon and to obtain clear digital subtraction images by interposing odd/even field memory in parallel, a mulfiplier and a subtractor between an A/D convertor and buffer memory. CONSTITUTION:A video signal of an interlace sytem from an X-ray TV set 1 is digitized and logarithm-converted by an A/D converter 2 and a logarithm converter 3, respectively, and fetched into odd/even field memories 4, 5 for exclusive use. Out of the contents of respective memories 4 and 5, the newest picture and the other are multiplied by 1 and K-times by multipliers 6 and 7, respectively, and subtracted by a subtractor 8. Out of the outputs of the subtractor 8, the image in which a contrast medium is not injected and the image with a contrast medium are fetched into a mask memory 9 and a write memory 10, respectively. The contents of both memories are subtracted by a subtractor 11, D/V-converted and recorded in a VDR13 or/and VTR14.
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