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Old 03-19-2013, 10:09 PM   #1
C8H10N4O2
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Cover Quality

So I am one of those OCD types that hate it when I have covers that don't look good. I know that Quality Check will identify small covers, but I have been working on a plugin that will do some additional checks:

In process:
  • Determine if a cover is mostly white. I have noticed that some covers come down with a huge chunk of the image being white and I want to identify those.
  • Determine if a cover is misshapen. I don't like odd shaped covers, so I want to identify those, too.
  • Determine if a cover is too small. Quality Check will do this, but since I'm implementing these other things, I might as well put this in.

Still Analyzing
  • Determine if a cover is out of focus. I have looked at several algorithms and I know that they work for photos, but I still need to figure out if it will work for covers.

Does this type of thing interest anyone? If it does, is there any other functionality that would be good to include?

Let me know what you all think.
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Old 03-20-2013, 10:41 AM   #2
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It sounds very interesting. I'd also think about checking for square (rather than rectangular) covers, which often come from the audio book version of a book.
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Old 03-24-2013, 07:28 PM   #3
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I am definitely interested. I have been getting covers from Amazon or Goodreads and putting them in Paint Shop Pro and fixing them, but that sometimes takes a long time if the cover is in bad shape.
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Old 03-27-2013, 07:57 PM   #4
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What I do is use Google Images to try to find a large size cover image and if it's large enough I reduce it down to 1024 lines. In most cases, this works. The cases where this doesn't work, I take the largest cover I can find and use it. This is when the eBook either has a generic cover or when the eBook has cover that's not as big as I'd like.

As for this plugin, go for it!
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Old 03-27-2013, 08:29 PM   #5
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I am trying a variety of things right now... Small size and oddly shaped covers are pretty easy to find. Finding covers that are mostly white is pretty easy but slow. What I'm doing now is down sampling the cover and then building clusters of color. Then I look at the clusters and determine the prevalent color. The problem with that is that it does generate a lot of false positives. In the past I did some work with Bayesian probabilities and I think this might be a way to determine good versus bad covers.

I'm not so sure about the focus thing yet. I'm still exploring.

Hopefully I'll have something to show in the next week or two.
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Old 03-27-2013, 08:33 PM   #6
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lots of those 300x300, Square covers that Google finds have whitespace on the sides. I usually shoot for a 300x500 range cover (smaller size, under 2X expansion on 600x800 display)
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Old 03-27-2013, 08:41 PM   #7
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I find covers display better if they are sized down then sized up.
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Old 03-27-2013, 09:05 PM   #8
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I agree. I go with the largest cover I can find and then shrink it down if I need. Sizing them up creates a lot of artifacts.
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Old 03-29-2013, 02:36 AM   #9
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Quote:
Originally Posted by C8H10N4O2 View Post
I agree. I go with the largest cover I can find and then shrink it down if I need. Sizing them up creates a lot of artifacts.
If you are making a cover quality plugin could you look into a cover download plugin that gets covers from google images instead of google books. With ebooks having gone mainstream usually the first 5 results for a cover by book name using search the internet plugin results in very high quality covers. So the ability to use google images from inside calibre would be really great.
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Old 03-29-2013, 03:49 PM   #10
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First things first... I need to get the plugin working identifying poor quality covers. Then we'll see where things go from there.
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Old 03-30-2013, 02:12 AM   #11
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Quote:
Originally Posted by C8H10N4O2 View Post
First things first... I need to get the plugin working identifying poor quality covers. Then we'll see where things go from there.
You are processing cover to find low quality covers. That would be a very processor intensive thing I think you would be better of just calculating the dimensions of covers 80-90% of the covers with white borders would be squarish instead of rectangular that should eliminate a large portion of bad covers.
Most bookstore recommend cover ratio to be 1:1.33 or 1:1.5 any cover not matching these ratios would likely contain white spaces or re-sized incorrectly

Low quality covers can also be processed by getting a dpi, dimentions and file size baseline and comparing cover images to that baseline.
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Old 04-05-2013, 11:25 PM   #12
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Sorry for the slow reply.

Right now I'm running a few scenarios. Processing them directly doesn't take too long, but I'm going to put in a variety of options.

Checking covers against a set of known set of qualities like the ones that you mention as well as HSL & HSV and potentially a few other data points could produce some pretty accurate results. We'll see what I can figure out.
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