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Change book page background
Posted: 2010-03-21T02:26:41-07:00
by dnorric
Hi I download a number of books from archive.org. Most of them are direct scans and so the page color is quite yellow and old looking. I want to essentially change the page to white color. Is this possible. I know its a large feat but just thought there might be someone already done so.
Cheers
Damian
Re: Change book page background
Posted: 2010-03-21T03:54:07-07:00
by snibgo
It certainly is possible, sometimes at the expense of legibility. Some of the books in there have already been thresholded, which introduces aliasing ("jaggies") into the edges of letters.
Often, a straightforward levels adjustment will do the trick well:
Code: Select all
convert in.jpg -level 10,70% out.jpg
You might also experiment with gamma and local adaptive thresholding (lat), and median. Optimum settings will vary with each book (and sometimes within a book). It might be easiest to experiment first with a GUI editor such as Gimp, then replicate the effect in IM, and do the batch conversion.
Re: Change book page background
Posted: 2010-03-21T04:42:57-07:00
by dnorric
oh my god that worked brilliantly. Thankyou very much
Re: Change book page background
Posted: 2010-03-21T05:57:44-07:00
by dnorric
What im noticing now is that the text has lost definition and is a bit specally black and white. Does anyone know to solve this
Cheers
Damian
Re: Change book page background
Posted: 2010-03-21T06:27:44-07:00
by snibgo
Post a link to an image, and to the "bad" result, and the command that created it.