I'm creating a custom scanfile for progressive jpegs. My goal here is to achieve a compromise between quality and the smallest possible size for the first scan. I don't care much about the other scans.
After some trial and error, this is the solution that worked well for my image set:
# DC coefficients
0,1,2: 0 - 0, 0, 6 ; # Scan 1
0,1,2: 0 - 0, 6, 5 ; # Scan 2
0,1,2: 0 - 0, 5, 4 ; # Scan 3
0,1,2: 0 - 0, 4, 3 ; # Scan 4
0,1,2: 0 - 0, 3, 2 ; # Scan 5
0,1,2: 0 - 0, 2, 1 ; # Scan 6
0,1,2: 0 - 0, 1, 0 ; # Scan 7
# AC coefficients
1 : 1 - 63, 0, 0 ; # Scan 8
2 : 1 - 63, 0, 0 ; # Scan 9
0 : 1 - 10, 0, 0 ; # Scan 10
0 : 11 - 63, 0, 0 ; # Scan 11
I have an idea on what's happening on scan 1 and scans 8 through 11.
I don't understand scans 2 through 7, I came with these lines through pure trial and error.
Does this scanfile looks correct to you guys?