04-01-2017, 01:00 PM | #1 |
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Send/Save Cover in Greyscale
Hi all,
I had an Idea for a "feature" that i think would be beneficial for some of us. Ad a checkbox that by update the "cover" transforms the Image into grey scale image. I use to have 2x for each book a high res cover for "pdf" / high dpi Android devices but also for epub / mobi generation 800x600 and they mostly only display grey scale anyhow. by this way I reduce the ebook size from 1MB avg to 200KB, not much in single book terms but for 100 books makes up quite some effort. \Pete |
04-01-2017, 01:42 PM | #2 | |
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Modify EPUB , which changes the Library Copy. Once done COLOR is lost for good. |
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04-01-2017, 06:02 PM | #3 |
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I concur. Also, different devices have different algorithms for translating color to grayscale, based on their own capabilities, so such a change is pretty much begging for complaints that some grayed book looks worse on whichever device.
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04-01-2017, 06:11 PM | #4 |
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I do want to keep the cover in color. If I read the book on my phone or iPad, I want to see the cover in color. If I read the book on my H2O, the H2O can show the cover in grayscale. Also,some Readers use 16 shades of gray and some use 8. The plugin will have no idea how to best dither the cover.
Last edited by JSWolf; 04-01-2017 at 06:23 PM. |
04-01-2017, 06:23 PM | #5 | |
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That's doubly true when making an observation that has already been made and agreed with: that this particular change would fit better in the "send to device" module (changing the copy on that one device) rather than in a module that alters the archive (changing it for all future use). There is value in the idea of sending a grayscale cover to a grayscale device - primarily in that grayscale images are much more compact, so such a change would permit more books to fit on the device - so while you or I may not mind the "hit" of sending full color to such devices, it's perfectly reasonable that others would want a way to change that. Personally, I'd love a smoother, more automatic way to use the color picker to change the cover page's background color - but I'm perfectly aware that this is a very niche desire, so there's not much to be gained by saying so. Thus, I keep my trap shut and use the existing tool to get what I'm after. Last edited by Rev. Bob; 04-01-2017 at 06:26 PM. |
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04-01-2017, 06:24 PM | #6 | |
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04-01-2017, 06:33 PM | #7 |
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In your edit, you completely missed that I said the same thing - just in more general terms - in the message right above yours.
My later point remains true, though. Even a "full" 256-gray image will be a much smaller file than a true-color image of the same dimensions, so sending a gray version would raise the number of books one can store on that device by a considerable factor... probably a more significant margin than the existing resize option permits. (True color is typically encoded as either three or four 256-level channels; grayscale only uses one.) |
04-01-2017, 07:04 PM | #8 | |
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If Kovid doesn't want to add the functionality to Send to Device (and Save to Disk), then you could create a private version of the plugin, as a number of other folks have done. The plugin already has the code to remove and inject cover images, so what's needed is 'a way' to create a greyscale image from the book's cover.jpg and inject that into the epub. There's a good chance that 'the way' is available from the calibre core. I'm sure the likes of Rev. Bob and Kovid will gladly offer their guidance. see post 1099 BR Last edited by BetterRed; 04-01-2017 at 08:37 PM. |
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04-01-2017, 07:43 PM | #9 | |
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04-01-2017, 07:50 PM | #10 |
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I have the perfect solution. What's needed is to add an option in the Calibre editor to convert an image to grayscale. You do most things you'd want to do with an image but not convert to graycale.
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04-01-2017, 08:33 PM | #11 |
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Why not just open the epub in Sigil, right click the cover.jpeg file, open it with any half decent image editor and save it in greyscale.
Why care if it changes the epub in the library, it doesn't change the book's cover.jpg file, which can be put back into the library epub with Polish Book in a heartbeat. And not a line of code need be written. BR |
04-02-2017, 08:06 AM | #12 | |
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Neither is true. You do what you want, and let other people do as they please. It's a big, wide world out there, full of room for lots of different opinions on this subject. It's neither your place nor mine to impose our opinions on others as The One True Way. I do some weird stuff, for example. Having noticed how many Open Road Media books use a certain color red bar across the top and bottom of their covers, I took advantage of my newly-installed calibre developer's environment to add a code snippet to my installation that changes the cover page's background color to that shade of red if calibre detects that they're the publisher. Will anyone else want to do that? Probably not - but I do, so I did, and I like it that way. Last edited by Rev. Bob; 04-02-2017 at 08:10 AM. |
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04-07-2017, 11:33 PM | #13 | |
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04-08-2017, 04:11 AM | #14 |
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Not a good idea (IMHO) because covers are not metadata.
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04-08-2017, 06:29 AM | #15 |
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