טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentGershikov Evgeny
SubjectOn the Role of Color Information in Image Processing and
Visual Communication
DepartmentDepartment of Electrical Engineering
Supervisors Professor Moshe Porat
Mr. Allen Robert Tannenbaum
Full Thesis textFull thesis text - English Version


Abstract

Color information plays a major role in image processing and visual communication although presently most algorithms and tools are developed mainly for monochromatic images. Usually, the processing of color images is performed either in the RGB color space or in another color space chosen rather arbitrarily, such as YUV or YIQ. In this work we propose new frameworks for color image processing and coding based on an optimized approach. These frameworks along with distortion modeling and analysis optimize the stages of coding and color processing for visual communication. The Mean Square Error (MSE) and the visual-oriented Weighted Mean Square Error (WMSE) are used to account for both quantitative and subjective visual fidelity. We exploit the high inter-color correlations of the RGB primaries to introduce a correlation-based coding approach rather than the ordinary de-correlation-based method, which is currently used in most algorithms. The two approaches are further generalized and unified to provide a general correlation/decorrelation-based framework.

The new color processing approach can be helpful in several fields of image processing, including image compression and image demosaicing. We show that for compression, the new framework outperforms presently available compression algorithms, including well established ones, such as JPEG 2000, while having comparable complexity. For other operations such as disparity estimation in stereo vision and image demosaicing, instead of using the ordinary RGB color space, the correlation of primary colors can be better exploited in optimized color spaces, resulting in algorithms that are superior to presently available methods. The proposed approaches to demosaicing and compression can be unified to provide a new framework of image compression using demosaicing where optimized color processing is used both in the coding and the interpolation of an image.

Our conclusion is that by optimizing the use of color information, major operations in image processing and visual communication could be improved quantitatively and visually.