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Old 06-06-2013, 06:51 AM   #35
Tex2002ans
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Posts: 2,306
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Join Date: Jul 2012
Device: Kobo Forma, Nook
Quote:
Originally Posted by eggheadbooks1 View Post
The difference in size between the jpeg and png is about 30 - 40%. About half his images are line art or text only, the other half are continuous tone (where the jpeg is smaller and better than the png). Some are in-between, probably 256-color. The client sent me fairly large jpegs, most of which have had to be downsized for the ebooks, so I should be able to get a decent png.
Quote:
Originally Posted by eggheadbooks1 View Post
TI did a quick text of two images; the quality was nearly identical but the file size was about -30%.
I showed off some work I did with compression of charts here (Example chart goes from JPG ~130 KBs to Indexed/Compressed PNG at 44.5 KBs (and looks WAY cleaner)):

https://www.mobileread.com/forums/sho...5&postcount=26

With black and white diagrams, the savings are even more pronounced than just these few color images (B&W/Grayscale/few colors compresses VERY well in PNG).

In this large project I am in the process of working on, I generated 175 very high quality (almost all were ~1200 px wide) PNGs of Tables/Charts/Diagrams. These compressed down to 9.10 MBs.

The equivalent 175 JPGs would be ~18 MBs (I just did a rough generation of JPGs from the original source). I could probably squeeze a few MBs out by optimizing the JPGs a little, but they will reach nowhere near 9.10 MBs.

JPG is a format built for "natural/photographic" images, and the algorithm is not the greatest when dealing with "artificial" type images.

When dealing with delivery fees and/or bandwidth costs for overly large book files, cutting needless MBs off of the book is very important!
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