Abstract
We present displacement estimated interframe (DEI) coding, a new coding scheme for 3-D medical image data sets such as x-ray CT or MR images. To take advantage of the correlation between contiguous slices, a displacement-compensated difference image based on the previous image is encoded. We have determined the best fitting distribution functions for the discrete cosine transform (DCT) coefficients obtained from displacement compensated difference images, and used the results in allocating bits and optimizing quantizers for the coefficients. The DEI scheme is compared with a 2-D block DCT as well as a full-frame DCT using the bit allocation technique by Lo and Huang [1]. For x-ray CT head images, our bit allocation and quantizer design using an appropriate distribution model resulted in a 13 dB improvement in the SNR compared to the full-frame DCT using the bit allocation technique. For an image set with 5 mm slice thickness, the DEI method compared to the 2-D block DCT gave about 5 percent improvement in the compression ratio on average and less blockiness at the same distortion. The performance gain increases to about 10 percent when the slice thickness decreases to 3 mm.
Original language | English |
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Pages (from-to) | 478-485 |
Number of pages | 8 |
Journal | IEEE Transactions on Medical Imaging |
Volume | 12 |
Issue number | 3 |
DOIs | |
State | Published - Sep 1993 |