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Walter Bright

Dr. Dobb's Bloggers

Reading PDFs on the Kindle Fire

December 02, 2011

I've read a lot of reviews of the Kindle Fire, and they don't discuss something very important to me — reading PDF files on the Fire. I bought one anyway in the hopes that it would do a good job of it. Here's my review (additional aspects of the Fire are well covered by other reviews).

Why PDFs?

I'm a bibliophile. I have thousands of books (including great piles of obsolete programming and tech manuals). The problem is the sheer size and weight of them — I cower at the prospect of moving. I'm also a hoarder, and so am unable to throw them away. So I decided to scan them, which would enable me to throw the physical book away, and yet satisfy my hoarding compulsions. Plus, there are all the other benefits of a digital version, which you all know and I won't bore you with.

Scanning is straightforward and fairly quick. I slice off the spine with a stack slicer from ebay, and run the result through a hopper-fed scanner. It takes about 5 minutes for a regular paperback. It then takes an hour for the scanning software to do the OCR, but it does that unattended.

Unfortunately, the OCR makes enough mistakes that it becomes annoying to read the text. It isn't worth correcting the text, either, for a once-through read. OCR'ing also loses all the formatting. (But I OCR anyway just so I can grep for text.)

(My friend Brad gave me a great tip about proofreading OCR scans: Scan it and OCR it twice at two different resolutions, so each OCR will make different errors. Run the resulting two files through your favorite difference merger (I like meld), and you'll be able to quickly fix 90% of the errors.

I prefer the resulting PDF as a series of images of the book's pages; 300 dpi, black and white does the trick nicely.

On my older eink Kindle 3, though, reading the PDFs is a bit klunky. The screen is a tad too small, and the zoom was more or less unusable. Switching it to landscape mode did work tolerably well, but only with pocketbook-sized pages. Anything larger was hopeless. I was anxious to see how the Fire stacked up.

Getting the PDFs onto the Fire was easy. Just plug a USB cable into a Windows box and drag-and-drop. No iTunes or other special software is required. The PDFs go into the "Docs" section. Unfortunately, you'll have to supply the USB cable; the one from the Kindle 3 will work. There doesn't seem to be another way to get PDFs onto the Fire, as 30Mb files cannot be emailed to it, and the Fire cannot browse shared files on a LAN.

Opening the Docs section on the Fire shows them arranged on the shelves of a "bookshelf". They show up as white squares with the name of the PDF in black text on the white squares. Many PDF browsers will show the first page of the PDF as the icon for the file, but not the Fire. Just a white square.

Tapping on the square will open the PDF file. It fills the whole screen, with no borders or controls. Tapping on the left or the right edges will move backwards or forwards through the PDF. Finger swiping works, too, but it's slow. Back to the tap.

The great news is that extra inch of screen size over the Kindle 3 makes a huge difference. Pocketbook images are readable. Examining the rendered text under a magnifying glass shows that the renderer will smooth out the black and white jaggies by putting in a few grey pixels. The Kindle 3 does that, too, but does a slightly better job of it. Text at the same resolution looks marginally better on the Kindle 3.

Pinch to zoom works too (yay!), but it felt somehow wrong compared with pinch to zoom on an iPad. It took me a while to figure out why.

  1. The obvious difference is that zoom is smooth on the iPad, but a little jerky on the Fire.

  2. On the iPad, the zoom centers around the stationary finger and the moving finger enlarges it. On the Fire, the zoom centers around the center of the screen, always, no matter which finger moves.

  3. On the iPad, moving both fingers also moves the image. On the Fire, moving the image is done separately — take both fingers off, put one on, then push the image around.

2 and 3 show that on the iPad, zooming works just like putting two fingers on a stretchy piece of paper, and moving and resizing it. The Fire simply does not work like that — the paper does not "stick" under one's fingers. Zooming and recentering requires two separate operations.

On a positive note, it does work and it does get the job done.

I've been enjoying reading books on the Fire. I do get a little more eyestrain than using the e-ink Kindle, but I expected that. Reading on the Fire works best in low-light conditions, the e-ink is best in bright light.

While my review might seem a bit critical, on balance I am very pleased with the Fire and its PDF reading abilities. The few issues should be addressable with software fixes, and I hope Amazon will do so. Meanwhile, I'll be scanning-in the next box of books from the attic.

Thanks to Brad Roberts for helpful comments on this article.

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