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Old 12-21-2010, 04:07 PM   #1
jordan13589
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Create readable .mobi files out of pdfs

Cross-post from Kindle:

So I've been trying to work on transferring my pdfs to the kindle 3, but I have run into some problems with formatting. When I transfer a pdf that is mostly text to a .mobi, and I then need to make the text bigger on the kindle to read the new .mobi file, it works fine. However, when I try to use calibre to make a .mobi file out of a pdf that has images throughout the text, or a pdf with multiple columns of text, the new .mobi file loses its ability to change text size when on the kindle; when I try to change the text size, the pdf image remains as a full page and won't change in size.

The only other option I am aware of is to keep them as pdfs and read them as is on the kindle. I prefer not to do this, though, as I find pdfs difficult to read and rarely worth the effort.

Is there any way to change the calibre instructions or directly alter the pdf so that the new .mobi file will have a pdf with images and will still change text size? Or a way to make a pdf with multiple columns into one stream of text? Or a way to unattach the images so that they lay above or below the text on the kindle?

Thanks.
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Old 12-21-2010, 04:33 PM   #2
Starson17
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Quote:
Originally Posted by jordan13589 View Post
When I transfer a pdf that is mostly text to a .mobi, and I then need to make the text bigger on the kindle to read the new .mobi file, it works fine.
It's likely this is a text-based pdf. They convert OK in Calibre.

Quote:
However, when I try to use calibre to make a .mobi file out of a pdf that has images throughout the text, or a pdf with multiple columns of text, the new .mobi file loses its ability to change text size when on the kindle; when I try to change the text size, the pdf image remains as a full page and won't change in size.
At this point, Calibre can't handle multiple column pdfs. Conversion will fail if it's a text-based multi-column pdf. If it's an image based pdf, conversion will succeed, but you'll only get images of pages full of text, so no text size management is possible. I can't be sure, but I suspect you are confused between image based pdfs (images of pages having text that look like text but are really pictures of text) and text-based pdfs. In the former, your pdf is just pictures. Only the latter has text that can be controlled with text size options.

When pdfs have both true text and graphics, conversion will work, but image placement relative to the text is often lost.

I suspect that this has nothing to do with whether the pdfs have graphics.

Quote:
The only other option I am aware of is to keep them as pdfs and read them as is on the kindle. I prefer not to do this, though, as I find pdfs difficult to read and rarely worth the effort.
I don't have a kindle, but I have the same issues with pdfs. Some are scanned page images of text, and some are true text. Only the latter type can be converted to other formats with any success.

Quote:
Is there any way to change the calibre instructions or directly alter the pdf so that the new .mobi file will have a pdf with images and will still change text size?
OCR the text images to convert to true text, then convert that.

As to your questions about images on the kindle, I can't help you at all.
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Old 12-21-2010, 04:47 PM   #3
jordan13589
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Quote:
Originally Posted by Starson17 View Post
It's likely this is a text-based pdf. They convert OK in Calibre.



At this point, Calibre can't handle multiple column pdfs. Conversion will fail if it's a text-based multi-column pdf. If it's an image based pdf, conversion will succeed, but you'll only get images of pages full of text, so no text size management is possible. I can't be sure, but I suspect you are confused between image based pdfs (images of pages having text that look like text but are really pictures of text) and text-based pdfs. In the former, your pdf is just pictures. Only the latter has text that can be controlled with text size options.

When pdfs have both true text and graphics, conversion will work, but image placement relative to the text is often lost.

I suspect that this has nothing to do with whether the pdfs have graphics.



I don't have a kindle, but I have the same issues with pdfs. Some are scanned page images of text, and some are true text. Only the latter type can be converted to other formats with any success.



OCR the text images to convert to true text, then convert that.

As to your questions about images on the kindle, I can't help you at all.
Thank you for your responses. I think I understand all of the answers and this is really helpful.

I'm intelligent but not specifically computer-oriented, so allow me to throw out my plan of action and let me know if this is the wrong course.

I have a rather large, mixed collection of pdfs (should be variations of image-based and text-based) that need converted to .mobi files. I'm going to use Acrobat's OCR option and do a multiple file conversion to first make them all text-based files. Then I will put these new files in calibre and convert to .mobi and hope for the best. Is this the best course of action? Should I change any of the layout or output options to get the best results?

Thanks.
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Old 12-21-2010, 04:52 PM   #4
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Quote:
Originally Posted by jordan13589 View Post
Thank you for your responses. I think I understand all of the answers and this is really helpful.
You're welcome.
Quote:
I'm going to use Acrobat's OCR option and do a multiple file conversion to first make them all text-based files.
You may not be really happy. The Adobe OCR isn't perfect and will likely need cleanup. ABBY is a bit better, but still needs cleanup. There are many who have been in your position, and there is no easy solution. If you can't read it in PDF format and can't get a better format, you're going to have to do a lot of work to get decent results.
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