| 摘要 |
PURPOSE:To remove the unequalness of every photographing or reading and to enhance accuracy by subjecting the image signals along the arrays of the picture elements in the main scanning direction and/or sub-scanning direction in the image of only the tissue of the bone part to averaging processing to obtain image signals for correction and obtaining corrected differential signals with the differential signals by each array of the respective picture elements. CONSTITUTION:The image 18 carried by the image signal logSA photographed by setting the voltage of a X-ray tube at a high voltage. The image 19 is obtd. by the low voltage. The tissues 18b, 19b of the soft part are subjected to subtraction processing; namely, computation is executed with each of the respective picture elements of the images 18. 19 to obtain the differential signal Ssub, by which the image 20 of the bone part is obtd. This differential signal Ssub has a shading and is subjected to the correction. Namely, the image signal along the arrays of the picture elements in the sub-scanning direction of the approximately flat part 20A from which the tissues of the bone part are removed is extracted from the differential signals at the arbitrary point thereof. The signal is then subjected to the averaging processing in the sub-scanning direction to obtain the image signal S3 for correction. The difference between this signal and the differential signal Ssub by every array of the picture elements in the sub-scanning direction is determined, by which the corrected differential signal Ssub' carrying the high-accuracy radiation image is obtd. |
