The Influence of Picture Quality Scale Measure on Choosing the Wavelet Transform during Image Compression

摘要

One important issue of the image compression is the quality of the resultant image. The Picture Quality Scale Measure (PQS) was used to improve this quality. This perceptual measure evaluates the visual distortions in color compressed image on the basis of the original and the resultant ones. This measure uses also a group of observers who are needed to evaluate the distortions. The implementation of PQS measure together with neural network enabled the independence of human observers. It was also possible to use this measure to influence the quality during the process of image compression. Each level of the wavelet transform was compressed with one wavelet function which caused the least visual distortions which were computed by Picture Quality Scale. The image was compressed with different transforms. The choice of a particular transform was taken on the ground of the PQS value. There were five different wavelet transforms to choose: Haar, Daubechies degree 4, Daubechies degree 6, Daubechies degree 8 and 5/3 transform. The image was coded with Embedded Zerotree Wavelet Coding (EZW).