Re: Image sizes

I also prefer a smaller file for reading on my screen. I have a pdf of the book "You Are Your Own Gym" by Mark Lauren and it is loaded with images of exercise techniques. The file wasn't even as big as some that you all are mentioning, it was over 50MB. But in my pdf reader it was slow to load and slow in scrolling while viewing. I was able to reduce the size of the file using Ghostscript and setting the images for "screen" mode which reduced the image dpi to something like 72dpi. No noticeable difference in image quality while reading on the screen. But the pdf loaded quickly and scrolled easily without pauses. The file size went down to around 16Mb. 

Someone who wanted to print out a copy of the same book would probably want much higher quality images so that they are sharp when printed. There's always a trade-off. 

To future-proof ebooks I think somebody else already mentioned storing original high quality scans of images. These wouldn't necessarily need to be downloaded by everyone who read the ebook, but could serve archival purposes in case somebody wanted to rebuild the ebook with highest quality images down the road. Or if someone was reading the book needed a high quality image to print a poster or look at a detailed diagram, they would have access to it. In this case for archival purposes, I would recommend that images are saved in a lossless format. Compressed jpegs can be  lossy or lossless. The standard allows for both. In that case it would be worth providing specific instruction on how to create lossless jpegs, which software to use and what settings to use to ensure a lossless image. 

> On Jan 26, 2014, at 11:27 AM, Chris Jones <[email protected]> wrote:
> 
> On Sun, Jan 26, 2014 at 09:28:05AM EST, James Adcock wrote:
> 
>>> There's a huge difference between the recommended-in-the-FAQ 40-60K
>>> size and tens of megabytes.  You could double the image resolution
>>> in both directions and it would still be a factor of *100* less than
>>> the tens of megabytes that you fear.
> 
>> A recent book I did has 82 woodblock prints. I cut the image sizes
>> down as much as I could with turning the woodblocks into horrible
>> messes.  The resulting sizes where 60-100k each.  The resulting PG
>> MOBI files (which granted, are Amazonian caca nowadays) are 13 megs.
>> And these are what I consider to be "small" images.  To well-preserve
>> the woodblock prints in their original glory would have required much
>> larger files.
> 
>> Again, I am looking for practical "best practices" advice, not to be
>> told that this isn't an issue. It is.
> 
> I recently bought The LaTeX Companion, 2nd edition published by
> Addison-Wesley. 
> 
> The epub version turned out to be 123MB.
> 
> I unzipped the epub and found that the graphics weigh in at 130MB and
> the embedded fonts at 26MB. There are no less than 1973 jpeg's ranging
> in size from ~10K to ~300K.
> 
> To add insult to injury, these "graphics" are no glorious woodblock
> prints.. many of them are just snippets of LaTeX code in plain old 7-bit
> ASCII that probably add up to less than 1MB all told.
> 
> Needless to say it takes a while to open this book on a fairly recent
> e-reader model such as the Kobo Glo'... and close to ten seconds with
> Calibre's viewer running on a top-of-the line laptop.
> 
> So maybe we're not only looking at air-time here but also at
> "accessibility".
> 
> As to the .mobi it is, wait for it..  231MB...!
> 
> I thought I'd mention this since this particular e-book comes from
> a reputable publisher (not so sure about who runs their e-book
> department..) and also because that's about one order of magnitude
> larger than your book.
> 
> Of course my little anecdoote has nothing to do with Project Gutenberg,
> and does not directly relate to your question... but I think it does say
> something about current trends in the e-book business.
> 
> Anyway, nice to know that someone who is volunteering their work to
> Project Gutenberg is concerned about good practices when those whose job
> it is to do so... apparently couldn't care less. 
> 
> I'm quite curious to know what book you are working on so I can take
> a look when it is published, if only to find out how you resolved your
> problem.
> 
> Best of luck,
> 
> CJ
> 
> P.S. Any reason why you would not publish a trimmed down low-res version
> and a larger high-res version of the book..?
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