Gives an idea on what PHRED encoding

get_PHRED.py

import glob
import os

inf = glob.glob("*.gz")
rlen = 76.0

for f in inf:
    tmp = f.split(".fastq.gz")[0]
    os.system("zcat "+f+" | head -n 4 | tail -n 1 > "+tmp)
    with open(tmp) as fin:
        cur = 0
        line = fin.readlines()[0].strip()
        for c in line:
            cur = cur+ord(c)
        print tmp,cur/rlen-33,cur/rlen-64
    os.system("rm "+tmp)   

@nbenzakour