Kindle DX 2 screen contrast improvement analysis

The improved Kindle DX 2 screen contrast is its big selling point. Amazon hasn’t really revealed too much about what led to this improved screen contrast.

Well, let’s take a closer look and see what factors might have helped improve the Kindle DX 2’s screen contrast.

Kindle DX 2 Screen Contrast Improvement – possible Factors

Here are the 3 factors that we can identify right away -

  1. Actual hardware improvements. eInk say the Pearl screen has 10:1 contrast as compared to the 7:1 contrast in previous versions. Quite frankly it doesn’t really seem like the hardware improvement by itself is 43%. In terms of measurements we have this from Bruce Wilson’s comment at Teleread -

    From density numbers alone – white is a little whiter, black is a lot blacker.

    Old White Kindle DX 1 (6 months old):
    white area density = 0.46, Lab = (65.8, -2.3, 0.6)
    black area density = 1.30, Lab = (26.6, -1.0, -2.2)

    New Graphite Kindle DX 2:
    white area density = 0.42, Lab = (68.2, -2.4, 0.9)
    black area density = 1.58, Lab = (18.5, -0.1, -3.6)

    I used a Datacolor Spectrocolorimeter model 1005. “Lab” is a color space measurement like RGB, only for print.

  2. Graphite Casing. Amazon have implied this is not factored into the 50% better contrast – However, it’s clear after playing around with the Kindle DX 2 that the graphite casing has quite an important role in making the screen look better.  
  3. Speckling on the Screen. There are very tiny speckles on the screen of the Kindle DX 2 when you zoom in. Click on the last photo on the Kindle DX 2 Photo page to see this speckling. When photos have noise like this added to them it improves their contrast – It’s hard to believe there could be any other reason speckling would be added to the screen of the Kindle DX 2.

We also have two additional possibilities –  

  1. Software improvements. Kindle software upgrades have improved Kindle screen contrast in the past by making the text bolder and it’s possible that Kindle DX 2 comes with some software improvements. Kindle DX 2 comes with firmware version 2.5.5 and it makes you wonder if that firmware version includes screen contrast tweaks.
  2. Additional changes in the screen hardware. There’s a very interesting mention in the official Kindle forum that the Kindle DX 2 screen is noticeably whiter if you tilt it a little rather than look at it straight on. For my Kindle DX 2 this is true – It’s noticeably whiter when tilted a little. Is this by design? Is this a byproduct of the new screen technology?  

The former is very, very likely while we understand too little about the latter to factor it in.

Breaking down the supposed 50% screen contrast improvement

After shooting a lot of Kindle DX 2 videos and taking a lot of photos and comparing screens in all sorts of lighting conditions it seems to me -

  1. Compared to Kindle 2 Global – Kindle DX 2 screen is 25% to 30% better normally, 30% better in sunlight, and 30% better when Kindle DX 2 and Kindle 2 are both tilted a bit. 
  2. Compared to Kindle DX 1 – Kindle DX 2 screen is 40% better normally, 45% better in sunlight or when both are tilted a bit.

There isn’t really a 50% improvement in screen contrast. It’s 40% to 45% when compared with Kindle DX 2 and 25% to 30% when compared with Kindle 2 Global. 

Furthermore it seems that this 40% improvement is broken down into -

  1. Half due to hardware improvements. If the spectrocolorimeter readings are correct hardware improvements might be responsible for as much as three-quarters of the improvement.
  2. A quarter due to the graphite casing. 
  3. A quarter due to the speckling.

The Kindle 2 Global screen is much closer to the Kindle DX 2 ‘better hardware screen’ than the Kindle DX 1 screen. This might be due to software tweaks or International Kindle 2s getting better screens or perhaps my Kindle 2 global was an exceptionally good version.

How did 50% screen contrast improvement and a graphite case and speckling and possible software improvements add up to 40%?

Well, it seems that eInk messed up and Amazon did as much as they could to make up for it.

Seriously – Look at the videos and photos. If you happen to have any of the earlier Kindles and the Kindle DX 2 compare them in various lighting conditions. If eInk’s claim is valid and there’s a 50% screen contrast improvement then it means that the graphite casing and the speckling and the software improvements (if any) contributed minus 10%.

The far more likely case is that eInk did a terrible job with their screens and improved just 20%. Then Amazon did a lot of brainstorming and came up with the graphite case and the speckling design for the screen and software improvements to get to 40%.

Amazon better hope Pixel Qi or Qualcomm Mirasol deliver color eInk screens soon because Amazon can’t keep compensating for eInk’s inadequacies with software upgrades and smart design decisions. The new Kindle DX 2 has managed to use almost every design and software trick possible to improve screen contrast (we’re including font sharpness improvements in the Kindle 2.5 upgrade). It’s had to because the actual screen technology from eInk isn’t improving fast enough.

Quick Summary 

Yes, Kindle DX 2 has a noticeably better screen. No, eInk isn’t responsible for all of the improvement. If eInk really would have improved their eInk screens 50% we would be looking at 70% to 75% better screen contrast on the Kindle DX 2.

6 Responses

  1. Hello
    Thanks for the great site. I’m interested in picking up my first e-reader and have been reading your site the last few weeks. (I’m a current iPad owner and very enthusiastic about it, but think a smaller, e-ink based reader would be better for dedicated reading based on using a friends for a few days.)

    I had a few comments about the new Kindle DX2 discussion and the Lab measurements for the white and black areas for the old and new displays .

    The “L” measurement is “lightness”, and required for determining contrast ratio. For the old, the contrast ratio measures 65.8 / 26.6 = 2.47, and for the new 68.2 / 18.5 = 3.69. This represents about a 50% improvement in CR as measured. (Note: the 2nd and 3rd parameters in the Lab measurement denote the “color” of the white point in the display and are not important for contrast ratio, but do indicate the whites are slightly different.)

    The important thing to note is that the measurements will not be affected by the surround (graphite case), and should not be affected by the speckling either. These two can have an impact for a human reader though, affecting in particular the adaptation point of the eye with the graphite surround.

    I can’t wait for the 6″ kindle with the new e-ink screen so I can finally pick one up.

    Thanks,
    Chris

    • Chris, thanks a lot for your comment. That helps clear up a lot. Any reason you think that might be causing the 50% better contrast plus graphite casing plus speckling to seem not exactly as high as 50%?
      Is human perception inclined to underestimate contrast improvements?

      As in do we think 50% better contrast will be better than what it actually is?

  2. >>>Is human perception inclined to underestimate contrast improvements?

    This is an interesting question because as I read this blog entry, I was wondering how you managed to come up with the 40%, 50% etc. improvement in contrast. The human visual system can’t really discern this sort of thing accurately, let alone assign a number I think.

    For example, here’s something fun to look at!
    http://www.sapdesignguild.org/resources/optical_illusions/images/BrainShadow.gif (checker-shadow illusion)

  3. [...] how it seems to have only 40% better screen contrast than the Kindle DX 2 – However, this Kindle DX 2 screen contrast analysis post and the comments confirm that the screen (by itself, without the speckling or graphite [...]

  4. [...] proven now that the eInk Pearl screen really does have 50% better contrast and Amazon has added software tweaks to help the contrast it still helps to have the graphite [...]

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