Compress images losslessly

jlynton · 04-21-2021, 06:42 AM

With Calibre 5.15, and now 5.16, the "Compress images losslessly" feature of the E-book editor his not working properly. If I use it to do a lossy compression it appears to work, and reports the new, smaller file size in the file browser, but if I save and close the editor, then later re-open the same file, the image will have gone back to it's original (pre lossy compression) size.

I am running Calibre 5.16 on Linux Mint 20.1 “Ulyssa” Cinnamon Edition.

kovidgoyal · 04-21-2021, 07:27 AM

I am guessing you are trying to compress the cover image. that is replaced from the calibre library every time you open the editor. You can turn that off under calibre itegration in the editor settings.

jlynton · 04-21-2021, 08:08 AM

Many thanks for your prompt reply.

I cannot find the setting you mention, see screenshot:
https://ibb.co/mqm7hFc

Is this a new setting? I have over years compressed cover images, but have never seen this happen before 5.15. Also, if I close the editor, then in calibre do 'Unpack Book', the size is as before compression.

kovidgoyal · 04-21-2021, 09:20 AM

"Update metadata embedded in the book when opening" and it has always existed.

jlynton · 04-21-2021, 10:44 AM

Thanks again Kovid.
I see how it works now. Would it be possible to separate it into two options, ie.
- Update metadata embedded in the book when opening
- Update cover.jpeg embedded in the book when opening

kovidgoyal · 04-21-2021, 11:06 AM

Not worth the work to me, sorry.

jlynton · 04-21-2021, 11:09 AM

I understand. In any case, thank you so much for all the work you have put into Calibre, it is EXCELLENT!

retiredbiker · 04-21-2021, 11:12 AM

To avoid this, I change the cover in the metadata after I have compressed it in the Editor. I use the "Set the cover for the book from the selected format" tool in the top right corner of the Edit Metadata panel. A huge un-compressed cover in the metadata will come back to haunt you not only in the Editor, but anytime the metadata is updated to the book file, like on sending to a device, updating metadata after changing comments, and so on.

jlynton · 04-21-2021, 11:38 AM

Quote:

Originally Posted by retiredbiker

To avoid this, I change the cover in the metadata after I have compressed it in the Editor. I use the "Set the cover for the book from the selected format" tool in the top right corner of the Edit Metadata panel. A huge un-compressed cover in the metadata will come back to haunt you not only in the Editor, but anytime the metadata is updated to the book file, like on sending to a device, updating metadata after changing comments, and so on.

Thank you so much, that is exactly what I wanted. I also see that one can Edit the metadata for multiple books, and select the 'Change cover' -> 'Set from e-book files' option.

JSWolf · 04-21-2021, 04:16 PM

I never ever have Calibre update the metadata. I do it myself in the editor. This way, I have full control.

04-21-2021, 06:42 AM	#1
jlynton Evangelist Posts: 414 Karma: 216544 Join Date: Feb 2012 Device: Kobo Clara HD, Moaan Inkpalm 5.	Compress images losslessly With Calibre 5.15, and now 5.16, the "Compress images losslessly" feature of the E-book editor his not working properly. If I use it to do a lossy compression it appears to work, and reports the new, smaller file size in the file browser, but if I save and close the editor, then later re-open the same file, the image will have gone back to it's original (pre lossy compression) size. I am running Calibre 5.16 on Linux Mint 20.1 “Ulyssa” Cinnamon Edition.

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04-21-2021, 07:27 AM	#2
kovidgoyal creator of calibre Posts: 43,926 Karma: 22669820 Join Date: Oct 2006 Location: Mumbai, India Device: Various	I am guessing you are trying to compress the cover image. that is replaced from the calibre library every time you open the editor. You can turn that off under calibre itegration in the editor settings.

04-21-2021, 08:08 AM	#3
jlynton Evangelist Posts: 414 Karma: 216544 Join Date: Feb 2012 Device: Kobo Clara HD, Moaan Inkpalm 5.	Many thanks for your prompt reply. I cannot find the setting you mention, see screenshot: https://ibb.co/mqm7hFc Is this a new setting? I have over years compressed cover images, but have never seen this happen before 5.15. Also, if I close the editor, then in calibre do 'Unpack Book', the size is as before compression.

04-21-2021, 09:20 AM	#4
kovidgoyal creator of calibre Posts: 43,926 Karma: 22669820 Join Date: Oct 2006 Location: Mumbai, India Device: Various	"Update metadata embedded in the book when opening" and it has always existed.

04-21-2021, 10:44 AM	#5
jlynton Evangelist Posts: 414 Karma: 216544 Join Date: Feb 2012 Device: Kobo Clara HD, Moaan Inkpalm 5.	Thanks again Kovid. I see how it works now. Would it be possible to separate it into two options, ie. - Update metadata embedded in the book when opening - Update cover.jpeg embedded in the book when opening

04-21-2021, 11:06 AM	#6
kovidgoyal creator of calibre Posts: 43,926 Karma: 22669820 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Not worth the work to me, sorry.

04-21-2021, 11:09 AM	#7
jlynton Evangelist Posts: 414 Karma: 216544 Join Date: Feb 2012 Device: Kobo Clara HD, Moaan Inkpalm 5.	I understand. In any case, thank you so much for all the work you have put into Calibre, it is EXCELLENT!

04-21-2021, 11:12 AM	#8
retiredbiker Addict Posts: 388 Karma: 1638210 Join Date: May 2013 Location: Ontario, Canada Device: Kindle KB, Oasis, Pop_Os!, Jutoh, Kobo Forma	To avoid this, I change the cover in the metadata after I have compressed it in the Editor. I use the "Set the cover for the book from the selected format" tool in the top right corner of the Edit Metadata panel. A huge un-compressed cover in the metadata will come back to haunt you not only in the Editor, but anytime the metadata is updated to the book file, like on sending to a device, updating metadata after changing comments, and so on.

04-21-2021, 04:16 PM	#10
JSWolf Resident Curmudgeon Posts: 74,319 Karma: 129333690 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	I never ever have Calibre update the metadata. I do it myself in the editor. This way, I have full control.

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