Objective: Explore different aspects of perception and their implications on displays
Perception is most commonly defined as the process of recognizing, organizing, and interpreting sensory information. It deals with the human senses that generate signals from the environment through sight, hearing, touch, smell and taste. Simply put, perception is the process by which we interpret the world around us, forming a mental representation of the environment. This representation is not isomorphic to the world, but is subject to many correspondence differences and errors.
In this lab, you will be using an Adafruit Metro Mini microcontroller platform to explore different aspects of visual perception. Through the Perceiving and Characterizing Parts of the lab sections, you will gain a better understanding of flicker fusion, color mixing standard, and light detection principles. You will also get to used industry
Lab Components
Components used in Perception Lab
- One common cathode RGB LED
- Resistors (2*150 Ω, 1*220 Ω)
- Adafruit Metro Mini
- Note: The Metro Mini is similar in function and hardware to the Arduino Uno microcontroller, therefore the Metro Mini can be programmed as an Arduino Uno through the Arduino IDE.
Part 1: Perceiving Color
Metro Mini Soldering and RGB LED Connection :
- Build a simple circuit by connecting the R, G, B pins of the RGB LED to three different I/O pins on the Metro Mini.
- Take note of which pin on the board matches the common cathode pin of the RGB LED.
- Be sure to use current limiting resistors to avoid damaging the LEDs.
Flicker Fusion Threshold Test
- Write a simple program in Arduino IDE that blinks an LED at 1Hz. You can use any color of the RGB LED. Check the link for more information on programming the Metro Mini. https://learn.adafruit.com/adafruit-metro-mini
- Increase the frequency until you can no longer perceive the flickering.
- Confirm the LED is still flashing by waving your hand in front of the LED.
- Now, repeat the experiment using your peripheral vision. Repeat the same experiment for each color of the LED.
Questions:
- What is the threshold frequency for visibility of flickering that you found (roughly)?
- Is there any noticeable difference in the frequency using your peripheral vision?
- What is the application of flicker fusion in displays?
Color Mixing
- Write a simple program that can mix the RGB LED into whatever color you want given the RGB parameter of that color.
- Using your program, display Columbia Blue (155, 221, 255) with your LEDs.
- To simulate how an RGB pixel on a display would change color, set your LED's to white (255, 255, 255) and transition through 5 different colors. At what frequency should you set the pixel's refresh rate?
Questions:
- Why is it difficult to find the RGB coordinates that will match exactly with the colors?
- Modern displays have resolution in the thousands! What are some issues in scaling up your one RGB pixel into an array of thousands?
Part 2: Characterizing Color
Analyzing luminance with luminance meter
Measure the luminance of the following objects in the lab:
Measure the luminance of the following objects in the lab:
- White paper
- Black paper
- Any RGB color from Part 1 using your RGB pixel
- Test Image 1 measured inside CEPSR10LE1 lab
- Test Image 1 on a computer screen
- Test Image 2 measured inside CEPSR10LE1 lab
- Test Image 2 on a computer screen
Questions:
- How might the luminescence of the objects differ if the measurements were done outside?
- Why is it important to calibrate the luminance meter before measurement?
Analyzing color with color meter
Measure the Lv, X,Y, Z, x, y parameters of the targets shown on the TV
Measure the Lv, X,Y, Z, x, y parameters of the targets shown on the TV
- Export the data (which includes Lv, X, Y, Z, x, y) that you measured for each target on the TV
Questions:
- Plot the data points in CIE color space with Mathematica and see if they match with the target's color
- Do your luminance values measured with the luminance meter match those measured with the color meter? If not why do you think there is a discrepancy?
- In a short paragraph, compare and contrast the RGB, HSV, and CMYK color spaces.
Fun Display Stuff!
Every year the Society of Information Display (SID) hosts a technical conference in the USA called Display Week. Included are a couple of interesting technical papers from the Display Week 2019 symposium on color.
Chromatic Adaptive framework for Apple's True Tone Displays. These displays detect ambient light color and brightness and automatically adjust the display to best optimize the illumination to use your device.
https://onlinelibrary.wiley.com/doi/epdf/10.1002/sdtp.13057
A paper by the CIE about their current work on wide color gamut and HDR. The paper presents the development of a new uniform color space!
https://onlinelibrary.wiley.com/doi/pdf/10.1002/sdtp.13059
Chromatic Adaptive framework for Apple's True Tone Displays. These displays detect ambient light color and brightness and automatically adjust the display to best optimize the illumination to use your device.
https://onlinelibrary.wiley.com/doi/epdf/10.1002/sdtp.13057
A paper by the CIE about their current work on wide color gamut and HDR. The paper presents the development of a new uniform color space!
https://onlinelibrary.wiley.com/doi/pdf/10.1002/sdtp.13059