| 摘要 |
PURPOSE:To obtain an energy subtraction picture of high diagnosing ability by finding out two signal values from a histogram of a differential signal and gradation processing the differential signal corresponding to specified output picture density. CONSTITUTION:Digital picture signals logSA, logSB are read out respectively from picture files 17A and 17B in a memory medium 17 and inputted to a subtraction arithmetic circuit 18. The circuit 18 weights signals logSA and logSB properly, and subtracts for each corresponding picture element and finds digital differential signal Ssub as shown in the expression. The signal Ssub is stored once in a picture file 19 and inputted to a picture processing circuit 20, and gradation processed in the circuit 20 through a signal converting circuit 20a basing on a gradation conversion table 20b. Gradation processed differential signal Ssub' is inputted to display unit such as CRT etc. and a reproduction recording device 21 such as a scanning recording device etc. and a subtraction picture is reproduced and recorded by the differential signal Ssub'. |
