Quote:
Originally Posted by Jim the Obscure
I'm in the process of assembling my first ePub book (Gertrude Jekyll, Wall & Water Gardens @ 454 KB / 91 pp of text in MS Word Doc) and will be using Sigil to do so once I've scanned the 150 odd b&w photographs (+/- 3 1/2" x5 1/2") in it. I did a test scan on my HP flatbed @ 300 ppi / 256 grayscale and got a 1.42 MB file (which is going to add up) so I tried the same grayscale at 150 ppi and got a 260 KB, which is better, but would still add up to about 40 MB in images alone - couldn't see much difference in quality between them. I will be importing them into Word 2003 and saving as HTML, Filtered, then opening in Sigil (which I’m still learning).
My question is (& I've searched a lot) what is the optimum PPI resolution for scans of b&w photographs to be imported into Sigil for display on both e-readers and in something like Calibre on a computer? What is the trade-off point between file size and quality in terms of resolution? Most of the ePubs that I've downloaded from places like archive.org are crawling with OCR errors from the Google scans and I've edited this text carefully for spelling (horror show of old & Latin plant names and tons of italics) and would like it to look nice but not be too huge. Also wondering about resolutions for colour scans too for future projects. (Best saved as JPEG's?)
I post a lot of cleaned-up text of (mostly) old gardening book excerpts on my blog (jimtheobscure.com) if anyone's interested – ps - wordpress.com doesn't support the upload of ePubs but I contacted Scribd support (looking for a place to park some) to inquire and they replied that they hope to be supporting them within the next quarter - now to work on Wordpress.
Thanks!
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Jim:
You're asking the wrong question, and truthfully, in the wrong forum--the moderator should move this to another forum, where you'll get more answers than you will here. The question has really nothing whatsoever to do with Sigil, it's about best resolution trade-off for the myriad devices out there. Generally speaking, we (at my company) use 96ppi (actual, not print rez) which is what the iPad still displays, although proponents of its later screens will tell you to significantly up-rez your images (to take advantage of the retina display). BUT, as you've noted, with 150 images, it adds up pretty quickly, so you have to trade-off the higher-rez for usability. Many older e-readers will crash if you try to feed them a huge file, particularly if it's not broken into many smaller chapters. We'll even down-rez images to 75ppi, depending on the type of book. If the images are illustrative, and not the main driving force behind the book, we'll do 75 if pressed for space. For "coffee table" type ePUBs, we'll make the image higher in rez and larger in size (for the pinch-zoom on the Fire and iBooks).
For what you're doing, I suspect 96 would be fine.
For on-desktop reading, AFAIK, the reader of choice tends to be ADE over Calibre for non-geeks. Geeks like Calibre, but I don't love it for reading ePUBS, myself. I love it for other reasons (cataloging), but not for reading.
I hope that helps?
Hitch