Friday, November 27, 2009

Kindle "Paper" is Too Dark

I wanted to like the Kindle DX. In an effort to bond to it, I downloaded two books I really wanted to read, The Lost City of Z, by David Grann, one of our alum, and A Most Wanted Man, by one of my favorite authors, John le Carre. However, the experience left me somewhat disappointed, and did not compare to the feelings of reading from real paper. Trying to pinpoint the sources of my discomfort, I realized one is that the "paper" behind the ink seems too dark. I decided to perform some scientific testing of my hypothesis. I warmed up our Epson Exression 10000XL with SilverFast v6.6 scanning software, created a scanner profile with an IT-8 target, calibrated our LaCie monitor with the GretagMacbeth Eye-One Display 2 colorimeter, now the X-Rite i1Display 2 (Who the heck comes up with these product names!). I turned on our SoLux 4700K lamp, which reproduces the full color spectrum of natural daylight. In other words, all the things one should do to work in the area of critical color management.

I then scanned a few "pages" of the Kindle DX, the New York Times, and of a newly published hardbound book. The scans included our IT-8 target, whose accuracy was verified. The results were measured in the Lab, or CIE, colorspace, which is designed to approximate human vision. It aspires to perceptual uniformity, and its L component closely matches human perception of lightness. However, to make the results easier to understand, L was converted to K, or grayscale. Here, K=0% means pure white, and K=100% describes pure black. It seems one would want the background of a reading to approach white (K=0%), and the actual printed ink to approach black (K=100%). So, let's see how our calibrated scans measure out. Naturally, the media should be scanned again for verification, and the included images are not the original 400 dpi TIFFs.

First of all, on the Kindle DX, the white background measures as K=42-44%. This is quite high, as mid-gray is K=50%. The black "ink" on the Kindle measures at K=78-80%. The Kindle's white frame measures an average of K=5%.

The New York Times front page paper stock measured K=21-23%, darker than I would have guessed, and the ink at K=68-70%. That was brighter than I would have guessed, and appeared almost pure black to me. I did notice a lot of variation in the inner pages, as much as paper up to K=23-25%, with ink at 73-77%. I found the Times to be considerably easier to read than the Kindle, even accounting for its larger page size.

I scanned Blood's A Rover, a recent popular printed fiction book by James Ellroy. I selected a book which did not have pure white pages, as I noticed many recent fiction books are getting away from that. Here, the paper measured K=7%, and the ink at K=75% (there are slight variations, these are averages). This was the easiest of the three media to read, by far.

The interesting discovery is that the Kindle had the darkest "ink," at K=78-80%, of the above scans, but to me was the hardest and least pleasurable media to read. I believe a major factor was the background "paper" color of K=42-44%, which is almost a mid-gray. If this deficiency can be corrected, I believe it will make using it a more pleasurable experience. It may not help that the outer Kindle frame is almost pure white, increasing the apparent grayness of its "paper." I also think a laminated plankette of bamboo, walnut, ebony, leather, etc. would be more pleasurable to hold and look at than a piece of easily smudgeable white plastic. It was also interesting that the Times' and book's ink, which seemed visually black, was only about 75% black.

Now, don't get me wrong, I believe the Kindle would be extremely useful and much better than printed paper in some situations, and I also believe there is a bright future for e-book readers. Amazon's e-ink is fine, but one thing they need to do is to come up with a better e-paper.


Bryan's workshop blog said...

What an ambitious analysis, Frank! That explains a bit of my experience with the Kindle 1.

PS: those are two books I'm looking forward to, too.

Frank Fulchiero said...

Thanks. I want to add a bit more later about how subjective appearances sometimes differed from actual measured values. That is, the perceived brightness is not necessarily what was measured by the scanner, though the scanner was accurate.

Both books were pretty good. The Lost City of Z is being made into a movie with Brad Pitt. We'll wait for judgment...