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Old 08-15-2020, 10:42 PM   #210
DNSB
Bibliophagist
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Posts: 47,418
Karma: 171313058
Join Date: Jul 2010
Location: Vancouver
Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos
Quote:
Originally Posted by koboy View Post
does the Clara have the original 8GB of storage?
Nope. It has a 32GB replacement uSD card. I like playing with my toys.

I actually did look at how many books I could stuff into the just over 6GB available with the stock 8GB uSD card. Mostly, this was done by reducing the cover size since in many of my epubs, the cover is a large chunk of the size. For my testing I went with 250xYYY (most of my covers are either 3x4 or 10x15 aspect ratio). I tried the Resize cover calibre plugin but was not happy with the results so I used a batch file to run Imageworsener with the height set to x0.25, convert to greyscale, etc. against a copy of my calibre library. I managed to stuff about 8000 epubs into the available space before the .kobo-images folder growth which I hadn't allowed for caused me to run low on space. The entire project took me longer than expected since I got into playing with dithering algorithms and the effects they had on the output.

The final batch file simply stepped through my calibre library and ran imageworsener against each cover file. After that was done, I used Modify Epub to embed the covers.
Code:
imagew.exe -grayscale -depthgray 4 -h x0.25 -cc 16 -gsf s -dither sierralite .\cover.jpg .\cover_sierralite.jpg
del cover.jpg
ren cover_sierralite.jpg cover.jpg
Edit: I've attached a sample of the original cover, the full size grayscale cover and the shrunken grayscale cover for one ebook. The ebook went from 1063KiB to 391KiB when the shrunken cover was used.
Attached Thumbnails
Click image for larger version

Name:	cover.jpg
Views:	170
Size:	700.4 KB
ID:	181360   Click image for larger version

Name:	cover_sierralite.jpg
Views:	155
Size:	25.7 KB
ID:	181361   Click image for larger version

Name:	cover_sierralite_full.jpg
Views:	156
Size:	281.1 KB
ID:	181362  

Last edited by DNSB; 08-15-2020 at 11:12 PM.
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