| 摘要 |
PURPOSE: To suppress the block effect of discrete cosine transformation by constituting a compressed image from an encoded differential image and an encoded down-sampled image and applying compression to the removal of the artificial structure of an original radiation image resulting from blocking. CONSTITUTION: An image 12a is generated by down-sampling 12 an original radiation image 11 and successively interpolated to the size of the original image 11. When the image 12a is interpolated, a smoothed image 14a is generated. A differential image 13a is generated between the original image 11 and interpolated image 14a by using an adder 13. Then an image 15a is generated by compressing 15 the difference between the images 14a and 11 by using 8×8 picture element block discrete cosine transformation together with sequential 12-bit data. The main artificial structure contained in the original image 11 results from the mismatching of the low-frequency component of the image 11 at the edge section of a block. When an encoded differential image 22 is generated by subtracting this low-frequency component, low frequencies are removed and, when the low-frequency component is separated and encoded, the artificial structure disappears except a very largely dynamically changing area. |
