Region based variable quantization for JPEG image compression

Introduces concepts that optimize image compression ratio by utilizing the information about a signal's properties and their uses. This additional information about the image is used to achieve further gains in image compression. The techniques developed in this work are on the ubiquitous JPEG still image compression standard [IS094] for compression of continuous tone grayscale and color images. This paper is based on a region based variable quantization JPEG software codec that was developed tested and compared with other image compression techniques. The application, named JPEGTool, has a graphical user interface (GUI) and runs under Microsoft Windows (R) 95. This paper discusses briefly the standard JPEG implementation and software extensions to the standard. region selection techniques and algorithms that complement variable quantization techniques are presented in addition to a brief discussion on the theory and implementation of variable quantization schemes. The paper includes a presentation of generalized criteria for image compression performance and specific results obtained with JPEGTool.