use a html page from ebook as the cover

[dwig]

The calibre Library creates its cover.jpg, along with its initial metadata, using the ebook's cover and metadata at the time the book is imported into the library. If you alter the book, with Sigil or calibre's Editor, and alter the cover it will not automatically be reflected in calibre's Library. If you use calibre's Edit Metadata dialog after editing the book, you have the option to select one of the book's formats and set the metadata and/or the cover from the contents of the selected book format. This is done using the appropriate buttons around the list of formats in the Edit Metadata dialog.

[stumped]

Originally Posted by jhowell

Calibre usually (but not always) copies a separate cover image thumbnail file when sending a book to an e-ink kindle device. The kindle will then either use this thumbnail copy, extract a cover thumbnail image from the book itself, download one from its servers, or leave the book with no cover thumbnail. This depends on the internal coding of the book (Format: MOBI vs KF8, CDETYPE: EBOK vs PDOC vs none, and ASIN) and the kindle firmware version.

You can see the thumbnail image files on your kindle by looking in the system/thumbnails folder. (Show hidden files to see the 'system' folder.)

? there must be some logic rules that govern all of that - and a flowchart or two ?
surely the programs do not roll virtual dice & then decide, Ok I'll treat this book that way.

the only path that i need to understand is starting from a bought or free epub being added to calibre , ending with a conversion reaching an e-ink kindle - complete with a cover
i get that amazon can be a black box operation at times but calibre usually but not always ...does not seem quite right

[BetterRed]

@stumped - theducks has beaten me to it, try the Generate Cover plugin. This is the sort of thing you can do with it, using my Billy Tea image.



Another way to get the image out of the epub you have, would be to right click it in the editor's files browser and use the Export image option, I suggest you put it on the desktop and then drop it onto the book details panel. That way you'll have a copy of the original at hand while you're exploring the options in the Generate Cover PI - you'll probably want to try different combinations of colours, fonts, border widths, positions etc.

Once you've generated a cover you like, you'll need to get it into the epub, I would use the Polish Book tool.

BR

[jhowell]

Originally Posted by stumped

? there must be some logic rules that govern all of that - and a flowchart or two ?

Its complicated. For example, to create a thumbnail file on a kindle calibre needs CDETYPE and ASIN metadata to be present in the book file. These strings provide the association between the book and the thumbnail. Kindle books converted from an EPUB by calibre will probably have these values set, but those obtained from some other source may not.

[BetterRed]

@stumped - have you watched Kovid's Video Tutorials. I found them very informative - watch a segment, then do it on a test library, rinse & repeat as necessary before moving onto the next segment.

BR

[BetterRed]

Originally Posted by BetterRed

@stumped - theducks has beaten me to it, try the Generate Cover plugin.

...

Once you've generated a cover you like, you'll need to get it into the epub, I would use the Polish Book tool.

@stumped - and, you'll probably want to keep the original image as it is before altering it with the Generate Cover PI, problem is where to keep it, ideally you'd want it in the book folder so that it doesn't get lost.

One way to do that is to convert it another image format that can be dropped into the book details panel. But there's a Catch-22, when a common image format file (jpeg/jpg, tiff, png, webp, bmp etc) is dropped into the Book Details panel Calibre will treat as a replacement cover. So you either need to convert to a really oddball format like JNG, or exclude a format via Preferences->Tweaks viz:



BR

[dwig]

Originally Posted by BetterRed

@stumped - and, you'll probably want to keep the original image as it is before altering it with the Generate Cover PI, problem is where to keep it, ideally you'd want it in the book folder so that it doesn't get lost. ...

The easiest way to keep the original covers for each of the pieces is to keep a copy of the complete unaltered omnibus in the library as an additional book. That way there are no problems with calibre "cleaning house" when some alteration is made to one of the single book entries.

[BetterRed]

@dwig - what do you mean by calibre 'cleaning house', are you implying calibre will lose data on a whim, that's never happened to me over the past four years on four libraries totalling 130+K books.

The problem with relying on the original omnibus book, is that you have to first find the omnibus book, then find the right image within it etc, etc.

I break out articles from composite journals and store them as individual books almost every day, there's often a picture I can use to create a cover, if not I filch one from somewhere. I find it much easier to keep a copy of the picture with the article as a JNG, then should I want to redo the cover I can convert it and save it as cover.jpg via the View a specific format tool and then fire up the Generate cover PI - all with the same book selected, without ever leaving the book list - i.e. no undercover skulduggery or faffing around finding the original composite journal.

The extra resources used in storage and backup processing aren't worth saving, on the other hand my time is a finite resource, relatively and absolutely, so it always trumps a few megabytes and processor cycles :lol:

BR

[theducks]

BR
I think he means: Running Library Maintenance and clearing errors (extra files)

[BetterRed]

Originally Posted by theducks

BR
I think he means: Running Library Maintenance and clearing errors (extra files)

@theducks - but if you add the JNG (or TIF if it's in the exclusion list) properly, i.e. by dropping it into the book details, or the Formats box in MDE, or via Add Books->Add files to selected book records there won't be any extra files. Extra/missing files only come about when one adds, renames, or removes library files and folders outside of calibre.

Calibre will retain any file type in a book folder, providing it is told about it when it's put there, including when a book's title or author is changed, or the book is copied or moved to another library and so on and so forth, etc.

But I know you know all that, I think many folks don't realise that calibre will store and retain anything in a book folder. I keep the bat and cmd files to start the server and browser for each library in a Book titled !Server by !Admin in the library

BR

[stumped]

to clarify - I appreciate all the help but some of the posts are telling me how to extract an image and use it for cover image, which is easy...

in this book though, each single book cover has been re-created for the omnibus as a html text + image page. as per the sample code I posted back at #5
.
I wanted the whole thing - the image AND the text layout - converted to an actual cover image..
some of the suggestions just talk me through grabbing only the relevant image, but lose the associated text
I accept there is probably no way to automate fro text+image, though I will look into what the epubsplit plug in can achieve. There are 22 books in the omnibus - to many to want to redo covers one at a time via screengrabs, paint,, save as...

[BetterRed]

@stumped - if you want further help, you should consider doing what I suggested in post #4 - post a scrambled version of the book so that the bookmaking experts can see where you're starting from.

The html file isn't the only object that needs to be considered, the CSS and the manifest, spine and guide sections of the content.opf file also play role.

If you don't want to do that, then create a titlepage as I showed you earlier, then by looking at how it relates the other objects, you should be able to work out a template to help you transform what you have into what you want for the other 21 books.

Unless epubsplit can do it, which I first suggested you look at yesterday, in post #2, I don't think you'll find a tool that will do what you want automatically.

BR

[stumped]

no i think I am done here, thanks - posting a scrambled 50Mb file is not practical- it's a huge book for kids with many colour pictures
and as I have explained over and over, the issue is just getting from a "cover" that has been recreated at HTML text + img, to a single image.

the CSS etc does not matter, as the generic question is just how to save/convert a single HTML text_ + image file within an ebook into a single composite image, without resorting to screen grabs. [ i think screen grabs is the only solution, actually]
I already posted the entire " book cover" html code in post #5.
I can create a titlepage as per your formula, which looks fine, but that is still a html text+image combo which needs to be transformed into a single image for calibre to treat as a cover image.
I am satisified with the outcome, I now know what can and what can't be automated, and the capabilities of the various suggested tools and plug ins.
i will PM you a screen grab

[dwig]

Originally Posted by theducks

BR
I think he means: Running Library Maintenance and clearing errors (extra files)

Exactly, this...

...and anytime you alter the title or author name which triggers calibre's altering the file structure (new folder names).

Keeping an extra book, the omnibus, in the Library is the easiest way to keep the original covers unaltered. It does not provide the easiest way to extract the originals for other use, perhaps.

What approach is best for an individual user depends largely on the frequency and likelihood that they need to access the originals. If access is either very infrequent or unlikely, then the easiest "archive" method would be best. Only if access will be frequent would it be worth the effort to extract each, store them in some reuseable form, and manage these is some reliable way with appropriate backups. Storing them as extra files in a calibre Library is not particularily reliable unless calibre is aware of the files and thinks that they are simply different formats of the same book.