Improvement of JPEG XL Lossy Image Coding Using Region Adaptive DCT Block Partitioning Structure

The Joint Picture Expert Group (JPEG) committee has been standardizing next-generation image compression, called JPEG XL, to meet the specific needs for a responsive web, wide color gamut, and high dynamic range. XL supports lossy lossless compression. A variable-sized discrete cosine transform (DCT) block is used partitioning method regarded as critical function performance of XL. current DCT in highly dependent on compression rate tends assign small-sized blocks homogeneously textured regions (HTRs) having similar or regular patterns. We propose region-adaptive that assigns larger HTR. proposed identifies HTRs by using combined metric employing sum-modified Laplacian, zero-crossing, colorfulness measuring region homogeneity. Objective, subjective, visual comparison evaluations with ten images recommended working group were provided show improvement coding performance. shows its superiority terms efficiency evaluated six objective metrics, subjective tests 15 participants, improvements HTR, gains execution time.