A pseudo lossless image compression method

To present a pseudo lossless compression which modifies the noise component of the bit data to enhance the compression without affecting image quality? The hypothesis behind the study is that the bit data contaminated by noise can be manipulated without affecting image quality. The compression method comprises of three steps: (1) to estimate the noise level for each pixel, (2) to identify those bits contaminated by noise and replace them with zero, (3) to perform a lossless data compression on the processed image. The compression ratios are 3.10, 5.24, and 6.60 for CT, MRI, and digitized mammograms respectively, for the new method which shows a 36.8%, 62.7%, and 125% increase for the three data sets than original data. The processed images are evaluated by two image enhancing techniques: window/level and zoom. They are indistinguishable from original images. The proposed method demonstrates an improvement more than 40% in compression ratio than original image without deterioration in image quality. The qualities of processed images are the same as compared with those images by loosy JPEG2000 image compression at compression ratio around 10.