Disabling OCR while converting a PDF to AZW3 (or, other kindle friendly formats)

noduskfever · 05-25-2016, 02:11 PM

I have some scanned pdf books which I want to read in my Kindle Paperwhite.

In Kindle PDF files has no thumbnails (covers are not shown in the library).

So, to get the thumbnail I wanted to covert them into AZW3 as this format supports bookcovers as thumbnails in Kindle's My Library. But when I tried to convert the PDF the OCR automatically tried to generate texts from that scanned PDF which I did not really like because they mess with the original formatting.

Now, is there anyway to disable the OCR while doing the conversion have have the images scanned from the PDF to keep in the AZW3 (or, any other kindle thumbnail friendly format)?

However, I have noticed that if the pdf book is not english, the OCR does not work, and it keeps the scanned pages in AZW3, and that's what I exactly want, with english books too!

theducks · 05-25-2016, 04:05 PM

Calibre does NOT (can't) do OCR

dwig · 05-25-2016, 10:21 PM

As theducks said, calibre does not do OCR so it must be a case of the PDF having OCR text in addition to the bitmaps of the scanned pages and that calibre is using this text in its conversion.

I don't know it there is a way in calibre to force it to ignore the text and only use the bitmaps. There is a workaround. If you use a "virtual printer" utility that installs a printer driver that streams its data to a file in PDF format instead of to a hardware device the resulting PDF will be "flattened" with only a bitmap for each page. You would then import this "flattened" PDF into calibre to perform that PDF>AZW3 conversion.

I've used both Bullzip PDF Printer and PrimoPDF on Windows for similar tasks in the past. My issues had been with PDFs that used partially transparent objects that became opaque and obscured the text below them, but the technique should work as well for the OP's problem. I would think that the MacOSX's built in service for printing to PDF (found in its normal print dialog) should work as well.

kovidgoyal · 05-25-2016, 10:22 PM

calibre does not do OCR -- if you are seeing text in the output, then t was present in the input.

noduskfever · 05-26-2016, 04:42 AM

Is there any way to clear the ocr text in the pdf files so that I can only have the scanned book pages in my azw3 files?

Divingduck · 05-30-2016, 08:11 AM

A quick solution within windows is printing the PDF as XPS (Microsoft XPS Document Writer, this driver is part of windows) and import the XPS file again as PDF with your external PDF converter.

05-25-2016, 02:11 PM	#1
noduskfever Junior Member Posts: 2 Karma: 10 Join Date: May 2016 Device: Kindle Paperwhite	Disabling OCR while converting a PDF to AZW3 (or, other kindle friendly formats) I have some scanned pdf books which I want to read in my Kindle Paperwhite. In Kindle PDF files has no thumbnails (covers are not shown in the library). So, to get the thumbnail I wanted to covert them into AZW3 as this format supports bookcovers as thumbnails in Kindle's My Library. But when I tried to convert the PDF the OCR automatically tried to generate texts from that scanned PDF which I did not really like because they mess with the original formatting. Now, is there anyway to disable the OCR while doing the conversion have have the images scanned from the PDF to keep in the AZW3 (or, any other kindle thumbnail friendly format)? However, I have noticed that if the pdf book is not english, the OCR does not work, and it keeps the scanned pages in AZW3, and that's what I exactly want, with english books too!

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05-25-2016, 04:05 PM	#2
theducks Well trained by Cats Posts: 29,782 Karma: 54830978 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	Calibre does NOT (can't) do OCR

05-25-2016, 10:21 PM	#3
dwig Wizard Posts: 1,613 Karma: 6718479 Join Date: Dec 2004 Location: Paradise (Key West, FL) Device: Current:Surface Go & Kindle 3 - Retired: DellV8p, Clie UX50, ...	As theducks said, calibre does not do OCR so it must be a case of the PDF having OCR text in addition to the bitmaps of the scanned pages and that calibre is using this text in its conversion. I don't know it there is a way in calibre to force it to ignore the text and only use the bitmaps. There is a workaround. If you use a "virtual printer" utility that installs a printer driver that streams its data to a file in PDF format instead of to a hardware device the resulting PDF will be "flattened" with only a bitmap for each page. You would then import this "flattened" PDF into calibre to perform that PDF>AZW3 conversion. I've used both Bullzip PDF Printer and PrimoPDF on Windows for similar tasks in the past. My issues had been with PDFs that used partially transparent objects that became opaque and obscured the text below them, but the technique should work as well for the OP's problem. I would think that the MacOSX's built in service for printing to PDF (found in its normal print dialog) should work as well.

05-25-2016, 10:22 PM	#4
kovidgoyal creator of calibre Posts: 43,843 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	calibre does not do OCR -- if you are seeing text in the output, then t was present in the input.

05-26-2016, 04:42 AM	#5
noduskfever Junior Member Posts: 2 Karma: 10 Join Date: May 2016 Device: Kindle Paperwhite	Is there any way to clear the ocr text in the pdf files so that I can only have the scanned book pages in my azw3 files?

05-30-2016, 08:11 AM	#6
Divingduck Wizard Posts: 1,161 Karma: 1404241 Join Date: Nov 2010 Location: Germany Device: Sony PRS-650	A quick solution within windows is printing the PDF as XPS (Microsoft XPS Document Writer, this driver is part of windows) and import the XPS file again as PDF with your external PDF converter.

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