1998 Volume 54 Issue 11 Pages 1281-1286
We examined the digital image resolution of an indirect radiographic system with an I.I. and television camera by using the ratio of contrast to square wave output. Because the output medium of the last image was a CRT with variable contrast, the output value was digitized. In terms of the ratio of contrast of the rectangular wave of digital images obtained from this device, the vertical direction was found to be better than the horizontal direction. This is because sampling is done after removing the high-frequency ingredient for the series signal provided by scanning at the time of digitizing. Further, the field of view of the I.I. was small, and the ratio of contrast to the rectangular wave was high. However, the value became almost the same as that obtained when a cross axis of the contrast ratio was converted into space frequency per pixel in the digital image. Resolution deteriorated when pixel size decreased. Therefore, it is important to determine the size of the pixel in digital images.
