Author Topic: Is it necessary to reduce size of Kindle cover image before uploading?  (Read 544 times)

garygibsonsf

I ask because when I add the ebook cover to my .mobi file, it balloons up to sixteen megabytes. Or do Amazon have algorithms that reduce the overall file size back down to something like a megabyte?

I'm sure I knew this a year ago, the last time I put a book out, but I can't remember a damn thing.

The image is 300x2000 pixels, 300dpi, which dimensions I do recall came from reading a KDP help file somewhere.
 

Simon Haynes

300 x 2000 sounds off to me - way too narrow, unless that's a typo? Mine are 1600x2400 or thereabouts, and my ebooks are rarely over 1mb






 

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garygibsonsf

Sorry! Typo. 3000x2000.

It's starting to come back to me. I build my ebooks in Reedsy.com (much like Draft2Digital's ebook builder) except the files come out stupendously huge - like a 16 megabyte .mobi file for a 140 page ebook. Which is ridiculous.

I think what I used to do is then run it through Calibre, converting .mobi to .mobi, thereby getting a file just half a megabyte in size. Which is much more reasonable.
 

Simon Haynes

That's the wrong shape - you'd want 2000w x 3000h (and it's still too big.)  2400 high is plenty, and you should also set the jpg quality to 95%.

I recommend irfanview as a trivial way to resize images. Load up your image, Ctrl+R, change the height (and the width will update itself proportionally), then Ctrl+S and give it a different filename.

Don't save over the original because jpg is lossy, and the file quality will get worse every time you save it.

Also, never use PNG files for covers. They're wasteful for complex images.
 

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Denise

I ask because when I add the ebook cover to my .mobi file, it balloons up to sixteen megabytes. Or do Amazon have algorithms that reduce the overall file size back down to something like a megabyte?



They reduce it, but I'm not sure how much.

The current recommendation from Amazon is 2500 on the longest side. I know it used to be 2400, and I frankly hate 2500 because the numbers aren't round, but OK.

You can compress your image in places like this: https://shortpixel.com/online-image-compression

I recommend Glossy. It's also a good idea to have a smaller/compressed cover image because some sites ask you to upload it and have a size limit.
 

Tom Wood

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According to the KDP help pages at https://kdp.amazon.com/en_US/help/topic/G200645690

"Ideal dimensions for cover files are 2,560 x 1,600 pixels."

Which is particularly unhelpful to have the numbers backward!
 

TimothyEllis

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My cover guy uses 2820 x 4500. This comes out about 5mb or so depending on what's on there.

When I save my final cover version out of Photoshop in jpg format, I change the slider down from max to about 8, so the size of the image comes down to around 1mb. I upload that version. You cant see the difference for looking at it, but it makes a big difference to the size of the mobi and how much you get charged for download.
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Simon Haynes


I use three dos batch files.


File 1 is called xGen.bat, and is called by the second one.



REM change the next line to match your installation
set IVIEW="C:\Program Files\IrfanView64\i_view64.exe"

REM you can toy with these values
set FILTERS=/resample /aspectratio /sharpen=5 /jpgq=85 /contrast=20

REM really only needed once.
mkdir Thumbs

REM change jpg to PNG if that's what your source files are

%IVIEW% %1.jpg /resize_short=%2 %filters% /convert=".\Thumbs\%1_%2w.jpg"




File 2 is called xGenAllSizes.bat, and contains this:


REM you can remove lines or add new ones
REM the value is the length of the SHORTEST side in the converted file.

call xGen %1 60
call xGen %1 180
call xGen %1 500
call xGen %1 1600




Finally, file 3 is the one you set up with all your cover files in. This is called something like Resize.bat, and it's the one you actually run.
Don't put spaces in the filename, or you'll need to make some changes to all the files.
Don't include the extension.


Contents of file 3:

call xGenAllSizes Hal1
call xGenAllSizes Hal2
call xGenAllSizes Hal3



To use, put all three batch files into a folder with your covers, and add 1 line for each cover file to the Rename.bat.

Double-click Rename.bat and you'll end up with a Thumbs folder full of various useful sizes.

 

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Denise

According to the KDP help pages at https://kdp.amazon.com/en_US/help/topic/G200645690

"Ideal dimensions for cover files are 2,560 x 1,600 pixels."

Which is particularly unhelpful to have the numbers backward!

Yes, but that's a bit too narrow. Ideally the proportion should be 9 x 6. I've noticed even Bookbub, on your bookshelf, cuts the top if it's taller than 9 x 6, and it happens on other websites too.

If you want to keep the 6 x 9 proportion, and if you have a height of 2560, you should have 1706.666666666666666666666 for width.
 

Count Jeffula

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No, it's not necessary.  I upload covers that are 3000 x 4500 @ 300 dpi.  Amazon shrinks them down as necessary.  The file size for my longest book is 0.64 MB.
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No, it's not necessary.  I upload covers that are 3000 x 4500 @ 300 dpi.  Amazon shrinks them down as necessary.  The file size for my longest book is 0.64 MB.

It's the 300 dpi which is the thing there.

One of my recent ones is 2820 x 4500 999 dpi, coming out about 1.1mb.

So there is a huge difference in the files being uploaded, and what Amazon do with them. Mine in original size bloat my book sizes badly, hence me reducing them down to 1mb ish.

But one reason for HD covers, is Tantor wont use a cover which is of poor quality. So I've been making an effort to better quality ones they will use, even if I use less quality to upload with.

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dgcasey

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One of the things I'm seeing here is the penchant for loading .jpg files to KDP at 300 dpi. Totally unnecessary, unless you're talking about the paperback, which I'm guessing no one is with the dimensions everyone's using. The files don't need to be 300 dpi when uploaded. Sure, when you create the image, do it at 300 dpi and save a copy of it, but the uploaded file should be 72 dpi.

Why?

Because the image will get served at 72 dpi by the internet to the person viewing your book. Go and save a copy of the image on your product page and then open it up in your graphics program and you will see it's 72 dpi.

All my cover images get created at 1563x2500 at 300 dpi, then reduced to 72 dpi. I only upload a 300 dpi image for the paperback covers.
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She-la-te-da

You don't need to insert the cover into your file, Amazon does that for you. That way you only get one cover inside the book.

Also, as others have said, you don't need that large a file, and for ebooks you don't need anything higher than 72 dpi. Both will save you on file size, and thus delivery costs.
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I could be wrong about this, but I think I experimented with 300 dpi uploads and 72 dpi uploads with Amazon, and the file sizes were pretty much identical at the end, leading me to conclude that Amazon probably converts the image to the lower dpi automatically. However, that was back in 2012, so it's possible the process is no longer the same.


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KDP strips the cover out and inserts the separately-uploaded one regardless.