This week I have found a bunch of very chunky scans on archive.org - 300-700MB each. Check, for example, this heavy scan of "Gautamiya-Maha-Tantra" (this one is actually a Krishna-Tantra, by the way), it nibbles up 353MB on HDD - https://archive.org/details/gautamiya-maha-tantram-acharya-srinivas-sharma
My common method of optimizing via ScanTailor/NAPS2 [#see my detailed 2019 post] had failed to process all these chubby scans, so I have invented the new one.
ALTERNATIVE METHOD - STEP BY STEP:
STEP 01 - JP2 to JPEG via XnConvert. Archive.org always provides users with a set of JP2-sources, but NAPS2 rejects this format, so we need to convert JP2 to JPEG at first.
XnConvert handles this task easily: the conversion of about 300 JP2-files takes up around 10 minutes. You got to change only OUTPUT settings like on the screenshot below (see also on #plurk):
After the batch conversion you will get an increased output - for example, if you had, let's say, 300MB of JP2-files, you would get more than 600MB of JPEG-files.
STEP2 - Black and White trick in NAPS2. Now it's time to batchload all JPEG-files to NAPS2 and process them via "Image - Black and White" option.
Please note, that different scans can require various thickness tuning - I usually use 440 points - see the screenshot below (also on #plurk):
After Black and White conversion just press "Save PDF" and your optimized file is ready!
Actually, this B/W trick shrinks the output in the very enormous way. For example, the original scan of Gautamiya on archive.org is 353MB, while this method gives you just a 20MB (!!!!) pdf-file with the same quality!
Vishnudut1926, Moscow, July 2020
