AZW3 thumbnail very pixelated/grainy/low quality

superminh21 · 09-28-2016, 11:38 PM

I know there is a size limit for thumbnails for viewing on a Kindle PW (tiny versions of the book covers), so I am OK if the book cover is scaled down...

But man the compression quality is intolerable! The resulting thumbnail is a 117 x 240 px jpeg, grainy and hard to see any detail. Looks like the jpeg quality is only 75%.

I tried to switch (and delete) the thumbnail in Calibre - Edit Book window but it is regenerated every time I saved the book.

Is there any way to interfere with this kind of thumbnail quality issue? Urgh azw3 books are much harder to edit than epubs...

Barbara1955 · 09-29-2016, 02:33 AM

Switch to MOBI see what happens

jhowell · 09-29-2016, 11:17 AM

It is hard to be helpful with the little information you have given. Where do your AZW3's come from? Are they (and their thumbnails) delivered directly from Amazon or are you sideloading? If sideloading though calibre or manually? Are the files downloaded from Amazon, produced by KindleGen, or from calibre conversion?

The ExtractCoverThumbs program may be of use to you. It can regenerate Kindle thumbnails from MOBI and AZW3 files.

superminh21 · 09-30-2016, 10:17 AM

I sideload the AZW3 using Calibre, most of those are converted from EPUB and MOBI using Calibre. I have a few Amazon books but they don't have this issue (haven't tested many books anyway). I think the conversion tool of Calibre generates thumbnails from book covers with high compression.

I played with Kindlegen before; the output files do not even have thumbnails...

Thanks for the suggestion of ExactCoverThumbs, I will check if it overwrites the thumbs with better quality ones.

09-28-2016, 11:38 PM	#1
superminh21 Junior Member Posts: 4 Karma: 10 Join Date: Jul 2016 Device: Kobo Glo HD	AZW3 thumbnail very pixelated/grainy/low quality I know there is a size limit for thumbnails for viewing on a Kindle PW (tiny versions of the book covers), so I am OK if the book cover is scaled down... But man the compression quality is intolerable! The resulting thumbnail is a 117 x 240 px jpeg, grainy and hard to see any detail. Looks like the jpeg quality is only 75%. I tried to switch (and delete) the thumbnail in Calibre - Edit Book window but it is regenerated every time I saved the book. Is there any way to interfere with this kind of thumbnail quality issue? Urgh azw3 books are much harder to edit than epubs...

09-29-2016, 11:17 AM	#3
jhowell Grand Sorcerer Posts: 7,055 Karma: 91577715 Join Date: Nov 2011 Location: Charlottesville, VA Device: Kindles	It is hard to be helpful with the little information you have given. Where do your AZW3's come from? Are they (and their thumbnails) delivered directly from Amazon or are you sideloading? If sideloading though calibre or manually? Are the files downloaded from Amazon, produced by KindleGen, or from calibre conversion? The ExtractCoverThumbs program may be of use to you. It can regenerate Kindle thumbnails from MOBI and AZW3 files. Last edited by jhowell; 09-29-2016 at 11:20 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Grainy look on Paperwhite	willdude	Amazon Kindle	2	05-08-2016 10:10 PM
Epub to mobi using KindleGen creates really low quality images – advice needed!	Joefish	Kindle Formats	8	10-11-2015 07:08 AM
AZW3 to PDF images quality	dragoth	Conversion	11	06-19-2015 02:38 PM
Troubleshooting K3 KB not fully refreshing, pixelated text, some inverted colors	kibbler1138	Amazon Kindle	7	01-09-2013 02:08 PM
Grainy display?	teaspoon	Sony Reader	10	06-28-2008 04:55 AM

09-29-2016, 02:33 AM	#2
Barbara1955 Non-Techy Posts: 4,455 Karma: 15499273 Join Date: Feb 2011 Location: WV---USA Device: Samsung Cell Phone & Amazon Fires & Kobo eReaders	Switch to MOBI see what happens

09-30-2016, 10:17 AM	#4
superminh21 Junior Member Posts: 4 Karma: 10 Join Date: Jul 2016 Device: Kobo Glo HD	I sideload the AZW3 using Calibre, most of those are converted from EPUB and MOBI using Calibre. I have a few Amazon books but they don't have this issue (haven't tested many books anyway). I think the conversion tool of Calibre generates thumbnails from book covers with high compression. I played with Kindlegen before; the output files do not even have thumbnails... Thanks for the suggestion of ExactCoverThumbs, I will check if it overwrites the thumbs with better quality ones.

Advert