Illumina reports the score of each base in the read as a phred score. But, how is the total read quality calculated?Is it the sum of scores of all the bases in the read?
Any comments are valuable.
There are a lot questions here focused on read quality so your question is redundant -- you can find other questions relating to your topic by using the custom search.
I would also recommend this page -- FASTQ format and read quality -- to provide you some background on how the Phred quality score is calculated and what each character means.
Similar one was discussed here