Complexity reduction of wavelet codecs through modified quality control
Integer-to-integer wavelets are employed for low-complexity image encoders in embedded applications and used in combination with wavelet coefficient coders, such as EZW, SPIHT, SPECK and TSSP. In scalable coders bitstream creation is computationally expensive when individual coefficients are manipulated. In this paper, we study two options that move the quality control to earlier stages in the encoding process to alleviate this complexity problem: (1) to stage one of the TSSP and (2) to the integer wavelet transform. By inserting special functions based on premature bit-plane dropping, we effectively implement a quality-control step prior to the coefficient coding. For a typical usage scenario with full HD images, with option (1) we achieve an improvement of the processing speed of TSSP by 28%, while retaining the original bitstream and thus the ratedistortion performance. Furthermore, we have found that option (2) is generically applicable to other bit-plane based codecs, while offering nearly the same processing speed.