Calibre changes size of cover.jpg when copy to new Libary --> see PDF attached

icq70610 · 10-01-2010, 11:59 PM

Hi folks,

Calibre changes the file size of all covers if copying to a empty library!
Windows 7 32.bit / Calibre 0.7.21

What I did:

1) Create empty library

2) Copy Selection of books into new library

3) Checked filesize of cover.jpg in new library. and compare to old one

I copied approx 1000 + books and filesize changed by +25% also noticeable sometime *.lit files are not copied.

in the PDF you have it with step by step pictures and text

Thanks

Joe

DoctorOhh · 10-02-2010, 12:09 AM

Quote:

Originally Posted by icq70610

3) Checked filesize of cover.jpg in new library. and compare to old one

So it didn't change the dimension of the image the the filesize?

icq70610 · 10-02-2010, 12:50 AM

hi no it dosent change the dimensions.

im currently still investigating details but in all files the changes are present.

i extracted the DIFF of the image changes and you can see them attached.

if you look at the compare.jpg you will see the Quality settings changing from 75% --> 92% so it seems calibre is doing a preprocessing of the files before rewriting them.

Thanks

Joe

kovidgoyal · 10-02-2010, 01:37 PM

yes all covers are processed. Why is that a problem?

icq70610 · 10-02-2010, 01:59 PM

Hi,

basically for two things.

1) why should a copy books to library anyhow do a preprocessing? I was assuming that the copy process is simple a copy and a rename of the directory according to the naming structure.

BOOK TITLE (166) --> BOOK TITLE (23)

2) preprocessing the files and changing quality in jpg's especially when you have a small image increases the filesize without any further info. so I was wondering why my folder size was changing?

Was the whole procedure planned? I mean if there is a good reason why the increase should be there im not against. I just dont see one :-(

thanks for the quick reply.

Joe

kovidgoyal · 10-02-2010, 02:29 PM

It uses the same code path as adding books, which processes images to normalize them and replace transparent backgrounds with white ones.

10-02-2010, 12:50 AM	#3
icq70610 Enthusiast Posts: 49 Karma: 510 Join Date: Sep 2008 Device: PSR505	hi no it dosent change the dimensions. im currently still investigating details but in all files the changes are present. i extracted the DIFF of the image changes and you can see them attached. if you look at the compare.jpg you will see the Quality settings changing from 75% --> 92% so it seems calibre is doing a preprocessing of the files before rewriting them. Thanks Joe Attached Thumbnails Last edited by icq70610; 10-02-2010 at 12:57 AM.

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10-02-2010, 01:37 PM	#4
kovidgoyal creator of calibre Posts: 45,609 Karma: 28549044 Join Date: Oct 2006 Location: Mumbai, India Device: Various	yes all covers are processed. Why is that a problem?

10-02-2010, 01:59 PM	#5
icq70610 Enthusiast Posts: 49 Karma: 510 Join Date: Sep 2008 Device: PSR505	Hi, basically for two things. 1) why should a copy books to library anyhow do a preprocessing? I was assuming that the copy process is simple a copy and a rename of the directory according to the naming structure. BOOK TITLE (166) --> BOOK TITLE (23) 2) preprocessing the files and changing quality in jpg's especially when you have a small image increases the filesize without any further info. so I was wondering why my folder size was changing? Was the whole procedure planned? I mean if there is a good reason why the increase should be there im not against. I just dont see one :-( thanks for the quick reply. Joe

10-02-2010, 02:29 PM	#6
kovidgoyal creator of calibre Posts: 45,609 Karma: 28549044 Join Date: Oct 2006 Location: Mumbai, India Device: Various	It uses the same code path as adding books, which processes images to normalize them and replace transparent backgrounds with white ones.

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