Fig. 7
From: AfterQC: automatic filtering, trimming, error removing and quality control for fastq data
An example of automatic adapter detection and cutting. The offset makes the best alignment for this pair of reads is negative, which indicates that the length of inserted DNA is less than the sequencing length. When the offset is detected, it is trivial to calculate the overlapping region, and cut the adapter bases (outside overlapping region) from 3’ of both read1 and read2