Quote:
Originally Posted by Waldo3
OK I have been testing this week with the option
compress_news_images = True
This has dramatically reduced the average size of the NYT subscription recipe issues from 5-13 MB in the previous 2 weeks to < 5 MB this week. For some reason the size of last Sunday's issue dropped the most to 2.7MB. I was suspicious - I did not do an A/B test - but the content seems to be intact. Navigation and page turning on the Kindle Keyboard and Paperwhite is also noticeably faster. Better yet, there have been no Kindle crashes.
On my PC's 24-in monitor, using a Mobi to epub conversion with Firefox, the photos are somewhat blocky but reasonably detailed. The text in some charts was readable but marginal. I gather that using another Calibre device profile in this case, rather than a conversion, may have improved image quality, but even this approach was acceptable to me.
I also tried the compression option with a custom Ars Technica recipe and had similar size reductions.
For the NYT, at least, it probably makes sense to set "compress_news_images = True" as the default option.
|
There are a couple of other image compression options you might want to try to see if you get a better combination of image quality and size.
The setting compress_news_images_auto_size defaults to 16, which means the image compression target is set to w*h/16 bytes, where w*h are the (rescaled) image dimensions in pixels. You can set this to a lower number to set a lower compression target.
Also, instead of scaling images to your device output profile, you can set your own image scaling parameters using the scale_news_images parameter.
I use the following settings in my custom recipes because I often view the mobi files on my iPad as well as my Kindle Fire.
Code:
compress_news_images = True
compress_news_images_auto_size = 8
scale_news_images_to_device = False
scale_news_images = (768, 1024)
Today's NYTimes weighed in at 6.7MB which for my purposes is a good result. There are no visible compression artifacts on my iPad and the images are scaled to that screen size. The Fire simply rescales the images down to its screen dimensions.