Putting your iPhone under the microscope: big surprise about screen

I thought I knew my iPhone pretty well, but turns out in one big way it surprised me. The screen is not what I thought at all.

Not surprisingly, we have a microscope in my house and it’s hooked up to one of our computers. It’s a very flexible scope that allows both kids and adults to look at stuff under high power even it isn’t mounted on a slide. I was goofing around with it the other day to get it working again for one of my kids and thought I’d look at my iPhone screen. I don’t know why this idea came to mind, but I got a big surprise.

I decided to look at the clock on my iPhone. As many of you probably recall, the “analog” clock on the iPhone is white and has black hands…or at least I thought it was white. The big surprise was that there was no white in the clock when you zoom in. Instead, the “white” appearance of the background of the clock comes from closely spaced and regularly aligned red, green and blue rectangular areas of light.

You can see the red-green-blue arrangement (these 3 colored rectangles are called subpixels) in the picture above composed of three shots of the iPhone screen over the clock at 10X, 60X and 200X, respectively from left to right. I put the small superimposed rectangles in the 2nd and 3rd images to show roughly where I zoomed in for the next pic. Other areas of apparent “white” on the screen have this same red-green-blue subpixel thing going on too. Of course, I then turned to the Internet and learned that many handheld devices and even computer monitors apparently have similar subpixel arrangements and the nature of these impacts the quality of the images on the screen.

Interestingly, even the “black” hand of the clock on my iPhone screen appears to have the same subpixel arrangement but perhaps just dimmer? I don’t think there is actually some black color in there.

Sometimes when you look at something more closely it isn’t quite what you imagined, which is part of the fun of science more generally.

3 Comments


  1. Hi Paul,
    This is basic physics. Easier to make a bunch of light sources (or filters) that operate at different frequencies than to make machines that have dial-up color — thanks to quantum mechanics. (Einstein was the first to figure out that part of the problem, 1905.)

    Now the way it works in biology is similar but a bit different. Humans have 3 opsin genes that code for 3 proteins, each being tuned to a particular frequency. Hence the three “primary” colors. (Color blind people excepted.)

    But really, humans are totally backward with respect to color. The mantis shrimp, it would seem, has 12 opsins
    https://www.youtube.com/watch?v=F5FEj9U-CJM

    Now here is the interesting thing. Some types of monkey are color blind (only 2 opsins) but when scientists grafted in a human red-opsin-types gene, low and behold the monkey immediately was able to detect the red color in order to do simple tricks and get food.

    So, when are you going to get me a half a dozen mantis opsin-encoding genes because I’d really, really like to see the big picture…


    • Thanks, Brian. When I first saw the red, blue, & green, I thought “Physics!” and that the sub pixels perhaps combine to form white light?
      I heard about the mantis shrimp. Imagine being able to see through their eyes even for a short time…maybe our brains could still handle it even though accustomed to fewer colors/opsins input.

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