Testing gscan2pdf output formats

Lineart 300dpi 260x200mm scans
123 pages

PDF
Downsample to: no downsampling

Compression: Automatic
FileSize: 29.1MB

Compression: LZV
FileSize: 29.1MB

Compression: ZIP
FileSize: 29.1MB

Compression: PackBits
FileSize: 47.4MB

G3 and G4 encoding didn't work for me.

Compression: PNG
FileSize: 30.4MB

Compression: JPEG 75% compressed
FileSize: 221.7MB

Compared to my method of converting pnm through ps to pdf:
FileSize: 22.4MB (This is the smallest pdf on 300dpi)

DJVU
FileSize: 13MB

Compared to my method of converting pnm to djvu:
FileSize: 13MB (Equal size)

gscan2pdf Session
FileSize: 591.1MB

PNM
Sum FileSize: 114.6MB

GIF
Sum Filesize: 33.5MB

PS
not working.

TIFF
Can change compression method (LZW, ZIP, JPEG, PackBits, G3, G4, none)
not tested

JPEG
Can change compression quality
not tested