The unofficial Amazon Kindle Blog has a review of the Kindle 3 and as part of it the author measured the contrast of the Kindle 3, Kindle 2, Nook and Sony PRS-600. Go over to the blog to find out how he did this.

Here are his results:

He also has some measurements of the current draw of the new Amazon booklight/case and so can predict its Kindle battery life impact.

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1. I posted these numbers in response to some news article here some time back, but these are the measurements using my Spyder 3 Print colorimeter:

White Kindle DX:
background L*a*b = 65.8,-2.28,0.57. Density = 0.46
“ink” L*a*b = 26.61,-1.08,-2.23 Density = 1.30

Graphite Kindle DX:
background: L*a*b = 68.17,-2.36,0.92 Density = 0.42
“ink” L*a*b = 18.46,-0.14,-3.56 Density = 1.58

And for comparison, some paper print product densities (in the format ink/paper):

pulp paperback 0.87/0.19
old pulp paperback 0.79/0.21

By way of explanation, L*a*b is the CIELAB color space. “L” is lightness, 0 (pure white) to 100 (nonreflective black). “a” is the magenta(+)/green(-) axis, and “b” is the yellow(+)/blue(-) axis. Density is really a measuement of how much light is absorbed by the medium. In terms of optical paper brightness percentage, my measured numbers convert to the following [brightness = e^(-density)], each reported as ink/background brightnesses:

White Kindle DX: 27%/63%
Graphite Kindle DX: 21%/66%
pulp: 42%/83%
old pulp: 45%/81%

Contrast, as best I can figure out, is done on luminosity. But the L*a*b “lightness” isn’t the same thing, so I’m not sure if it is proper to use brightness, or use the lightness value, or even the density values.

I’m posting this to the original blog, too.

2. I posted these numbers in response to some news article here some time back, but these are the measurements using my Spyder 3 Print colorimeter:

White Kindle DX:
background L*a*b = 65.8,-2.28,0.57. Density = 0.46
“ink” L*a*b = 26.61,-1.08,-2.23 Density = 1.30

Graphite Kindle DX:
background: L*a*b = 68.17,-2.36,0.92 Density = 0.42
“ink” L*a*b = 18.46,-0.14,-3.56 Density = 1.58

And for comparison, some paper print product densities (in the format ink/paper):
http://www.kindleinuk.co.uk