HVS based Rate Control Algorithm using JPEG-LS with Applications to Wound Imagery

C. Grecos (UK)

Keywords

JPEG-LS ,rate control, image compression

Abstract

The JPEG-LS standard is attractive for compressing medical images because it combines relatively high compression rates with zero or minimal information loss. However it has two main drawbacks. First, the range of image qualities achieved is limited because the single information loss parameter (NEAR) remains constant through-out the compression process. We initially propose a multilevel information loss scheme which is able to produce many more different image qualities for the same compression rates. Second, JPEG LS rate control is not HVS based and results in equal information loss for both rough and smooth areas. The proposed rate control algorithm follows the HVS principle of texture dependent tolerance of information loss instead, by utilising the multiple information loss level framework. While JPEG-LS gives a limited range of image qualities corresponding to rate increments of 5-10%, we can achieve most of the image qualities in between for the same rates because of the multilevel scheme used. The quality of the reconstructed images after rate control is applied can also be shown to be closer to the original.

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