Where are all those Galaxy Nexus subpixels?

http://www.google.com/search?q=siemens+star+chart

Those curves are an illusion. They don't actually appear in the image. We see them because of the tiny, staggered parallel lines required to reproduce an angled line using a grid pixel array. You can optimize to reduce this effect by using different anti-aliasing techniques that are specific to the type of display you're using. Apple tends to favor "soft" anti-aliasing techniques over accuracy. They also have the benefit of controlling the entire software stack, so their image processing can optimize for the IPS display used in iOS devices.

Some people find the softness downright obnoxious, while others think it results in the most pleasing image. I prefer Apple's method.

Color perception is a very broad topic. It's one of those "why is the sky blue" questions that we've all pondered (and frequently arrive at a false conclusion). I'm not nearly knowledgable enough to talk about it with authority, but you should definitely do some Googling, and be sure to keep an open mind. The answer is probably not what you think.

This is what the test image looks at zoomed to 400% with no anti-aliasing and no additional processing. This is a pixel-by-pixel resolution of the mess at the center of that image:

http://i.imgur.com/WeoI4.png

When displayed 1:1 on a device, that mess will show up.

DPI is dots per inch. This is an indication of resolution density. When you scale the display of an image on a fixed size screen, you also scale the DPI. That is to say, you could use a 1 million DPI image, and still, when displayed at 1:1 on a smartphone, the DPI of the resulting image is the same (the extra pixels are clipped outside the boundaries of the screen).

Keep in mind that this test pattern should appear like a fractal. No matter how far you zoom in, the pattern will look the same. The points at the center should scale down to near infinite resolution. The resolution limitation is only that of the display device.

A more suitable test that gets closest to the hardware would work something like this:

* Start with an SVG test pattern

* Record the native resolution of each device in pixels

* Render the SVG test pattern with no anti-aliasing (or at least consistent anti-aliasing) at each target resolution

* Display the image on the device using a custom developed application that disables or avoids any internal scaling or image processing capabilities of the software

* Observe the results

If you wanted to test the rendering capabilities of the entire software stack, you should still start with an SVG and use whatever built-in components will render SVG.

Starting from a large bitmap tells us how well the bitmap scaling software works, but you shouldn't zoom to display at 1:1. You should allow the software to resize and see how well it scales.

Each of these is another step removed from the core question asked in the article: Does the pentile screen impact image quality? To answer this question, we must rule out other factors, such as software rendering capabilities.

The final error made is that of attempting to capture the results with a finite resolution capture device (a camera). At a pixel level, your capture would need to greatly exceed the resolution of the target display in order to examine the results at a pixel level or to reproduce the image in a way that objectively represents the perceived result to an audience not present at the time of testing.

With a film camera, you could test the limits of the lens and film. With a digital camera, you test the limits of the lens and sensor.

The regularity of a pixel array in a camera sensor or display results in the Moire pattern you see in these test images.

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