Study of EBCOT in Group-of-Column Skipping in Two Scans

Abstract

In Motion JPEG2000, embedded block coding with optimal (EBCOT) consists of Tier 1 and Tier 2 coding. In Tier 1, every bit-plane is scanned three times and coded in three channels. This means a long operation time, which may account for over 50% of total time of EBCOT. To reduce the time of compression and coding of JPEG2000, it is necessary to study the mechanism of Tier 1 coding, especially in the three-channel scanning mode. It has been found that validity flag ] [j i  is the first to be determined in the first and the second scan. If the validity flag is 1, then magnitude refinement (MR) coding is done; if it is 0, we need to determine whether the coding in validity channel is to be done. However, we propose the feasibility of combining the two codings together and perform scanning once. Then we only have to determine whether the coding is to be done for the pixels in the validity channel or in the MR channel. During the first scan, the value of validity flag i[j] will be determined only once, thus reducing the number of judgments. Therefore, the proposed process of EBCOT consists of 2 scans and coding in 3 channels. This reduces the number of judgment and scans and saves the time.