Objectives. Explain perception Analyze color perception Analyze vision Relate perception with color models

Transcription

1 Color Perception Ayse Kalkan-Savoy NSF GK-12 Fellow Vibes and Waves in Action Center for Advanced Computation and Telecommunications University of Massachusetts Lowell

2 Objectives Explain perception Analyze color perception Analyze vision Relate perception with color models

3 Perception What is perception? Cognition A single unified awareness derived from sensory processes while a stimulus is present

4 Light Is color light?

5 TEST 1

6 TEST 2

7 TEST 3

8 TEST 4

9 Color Perception Color is in our brain.

10 RGB Color Model Primary Colors: Red, Green, and Blue RGB Color Model: Used to display images in electronic systems First experiments with RGB: early color photography The first color photograph, taken by J.C. Maxwell in 1861

11 Y'UV Color Model Human eye is most sensitive to luminance Y' -> electronic brightness (luma) U, and V color information U = blue luma V = red luma Y' = R G B U = R G B V = 0.615R G 0.100B

12 Y UV Image Example An image and its Y, U, and V components (from Wikipedia `YUV,

13 Teacher: Ayse Kalkan-Savoy Period: Date(s): SETTING THE STAGE Essential Question Content Objective(s) (Student-friendly) Connection to previous or future lessons Science Lesson Plan Class: Algebra 1/ Engineering Is seeing knowing? None - Explain perception. - Analyze color perception. - Analyze vision. - Relate perception with color models. Critical Thinking Questions Key Vocabulary Perception, color, vision, image, sharpness, brightness, RGB, primary colors, luminance Materials Needed/Safety - Printed pictures will be given to students to gather thoughts on defining visual perception. ACTIVE INSTRUCTION Launch (Engage) Students will be divided into groups of four. Each group will have two sheets of pictures. Pictures will be M. C. Esher s drawings. Esher was a graphic artist, known for his mathematically inspired art work. Students will be asked to discuss what they see in the pictures for five to ten minutes. Then they will be asked to share discussions. After this activity they will be asked what they think perception is. Investigation (Explore) Students will be shown four sets of images. Each set will have four true-color images. One will always be the original. Three others will include color intensity modified images of the original. The intensity of red will be kept higher in one. The intensity of blue will be kept higher in another one, and the intensity of green *This template is available in electronic form. 1

14 Teacher: Science Lesson Plan will be kept higher in the fourth. The question posed to the students is: Which image is the closest to the original? During the perception test, each student will be asked to write down the answer first, so that they do not get influenced by their classmates. Instructor will tabulate the counts for Red, Blue and Green intensified images. The results will be compared to the tests and conclusions made by scientists. Note: Human vision is most sensitive to hues of green, then red, and then the blue color. TIME FOR REFLECTION Summarization (Explain & Extend) 1. The students will be grouped into two, or four. They will receive two pictures and will be asked to talk to each other about what they see. We will discuss perception, and visual perception. 2. We will discuss the physics of human vision. I will put a green (or red) apple on the desk, and ask the question How/Why do we see this apple as green? There will be short review of physics and human physiology of vision. We will talk about the light, visible light spectrum, cells of retina (rod and cone cells) that are activated by light. 3. We will test our sensitivity for red, blue and green through color test described in Investigation section. 4. We will talk about Red-Green-Blue color model, and why they are primary light colors. 5. Are there any other color models that are popular? There are. I would like to introduce YUV model. In this model Y is luminance. U and V are color difference signals. If time permits, I would like to talk about this model. Our vision is most sensitive to luminance. This model allows keeping the luminance value the same while we can modify U and V values to save data space. Assessment (Evaluate) Student will have a sheet of paper. The main ideas will be bullet point keywords. Students will be asked to take notes on their definitions during the class. There will be one question at the end of the class: In RGB models for computer screens, one color is created by assigning a value to between 0 and 255 for red, green and blue. As an example, blue is (0, 0, 255), and (255, 255, 255) maps to white color. What do you think black color values are in RGB model? Which number set can represent RGB colors? Homework None. *This template is available in electronic form. 2

15 Teacher: Science Lesson Plan *This template is available in electronic form. 3