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Learn about screen technology and human visual perception by investigating color images up close. Even the fanciest smartphone screen has only three colors.
Set your device to display a white screen. If you don't know how to do this, you can use this image by opening the link in your web browser, downloading it, or taking a picture. Be sure that the image is bright and appears solid white.
Note: To ensure your phone doesn’t “go to sleep” during this activity, you may have to regularly tap your screen or adjust your setting.
Make sure your mobile device is turned on and displaying white. Place the device on the microscope stage. Focus and carefully increase the power of your microscope until you see the lit red, green and blue lights. Where’s the white?
Now change the image on your screen so it shows another color. Look through the microscope to see what has changed.
Try looking at a photograph or an image showing a mix of colors. How do the colors you see on the screen with your naked eye correlate to what you see under the microscope?
Finally, try watching a video at the pixel scale. See how the colors change as the scenes in the video change.
Mobile device manufacturers take advantage of several visual processing tricks or optical illusions to display screen images:
By looking through the microscope, you can see all three illusions in action. Three colored subpixels make all the colors, images and moving pictures you see on your display screen.
To extend this activity, try looking at a variety of brands and models of smart/mobile devices. Are there any differences between the technologies of various models, like the shape, size, and spacing of the pixels and subpixels?
How does a device with a very sharp image compare with one that is not as clear?
Can you determine the relative ages of two devices just by observing the microscope images?
Here are a few magnified images of white light coming from several different phones (click to enlarge each image):
Samsung Galaxy Note 4 (2015)
Samsung Galaxy Nexus (2012)
Apple iPhone 5 (2012)
Our understanding of the phenomenon explored in this Science Snack is built on the work of many scientists.
Dr. Vivian Wing-Wah Yam is a Hong Kong chemist and in 2001 made history by becoming the youngest member of the Chinese Academy of Sciences. Dr. Yam’s research focuses on organic light-emitting diodes (OLED), which has led to more efficient displays for devices such as mobile phones and laptop computers. She has won many accolades for her contributions to photochemistry and continues to work toward the mission of offering safer and more efficient ways to produce artificial light. In the Pixels, Pictures, and Phones snack, you can learn more about screen technology and human visual perception by investigating images on your digital screens up close.
Test how well your brain can see patterns.
There’s more to seeing than meets the eye.
Not all shadows are black.
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Attribution: Exploratorium Teacher Institute