Overview

This is a second opportunity for students to interact with the Pixelation Widget, but this time they will work with color pixels. Students start off learning that each pixel uses red, green, and blue lights that can be turned on or off using bits. They will create more color variants using an increasing amount of bits per pixel, and apply their learning by approximating an analog color image using the widget.

Goals

Students will be able to:

Purpose

This lesson continues the story of how bits are used to represent digital images. Much like in the last lesson, students will use the Pixelation Widget to attempt to make digital approximations of analog images, this time in color. These images are produced using layers of abstraction, with each layer relying on the other to perform its process.

Students will begin to realize that analog color images have values that change smoothly and subtly, while digital images do not. The number of digital colors is also limited by the number of bits per pixel, whereas analog colors are unlimited.

Resources

Getting Started

Prompt: How many different shades of the color blue can you name? How many do you think there are in total?

Discuss: Have students share with a partner. Then, invite a few students to share what their partner said.

Discussion Goal: Start with having students name shades, but quickly transition to how many they think exist altogether. The goal here is to have students begin to wonder if computers can represent all of the vast number of shades of colors in our world. This should be a quick discussion. You can move on as soon as this point is made.

Remarks

Activity

For today's activity, students will again use the Pixelation Widget, which can be found in the CSP-Widgets Repository. While using the widget, students should use the "Full Color" setting for the challenges.

Note: This lesson includes color images in a number of places. See the teaching tip on the right for some additional guidance that may be useful when supporting students who are color-blind.


Teaching Tip

The directions are written in so that students who are color-blind do not need to be able to distinguish between colors to be able to complete the task. That being said, students who are color-blind may not be able to visually check their work in the same way as other students. You can suggest that students who are color-blind ask a partner to check their work at the end of each of these levels.

For the final challenge, it is recommended that students who are color-blind do the black and white gradient image.

Challenge 1

Remarks

Do This: Each student should try to make all 8 unique colors using 3 bits per pixel.

Challenge 2

Remarks

Do This: In the Pixelation Widget, make three rows of pixels. Generate all the shades of red in the first row, and then do the shades of green and blue in the last two rows.


Teaching Tip

Students who are struggling with the binary sequences should be encouraged to take out their Flippy-Do to help them count.

Challenge 3

Remarks

Do This: Students should again generate each shade of red, green, and blue in separate rows, this time using 3 bits per color.

Challenge 4

Remarks

Do This: Show students the images below. Then, each student tries to reproduce an image of their choice using the Pixelation Widget. They can try to reproduce the whole image or just a part of it.


A picture of the sky with wispy clouds. The image is a blending of white and light blue pixels.

A gradient that looks to be drawn with markers. The top of the image is magenta, which transitions smoothly into yellow at the bottom.

A painting that is splattered with pink, red, orange, and purple paint.

A black and white photo of a landscape. A cloudy sky stretches over mountains on the horizon, and in the foreground, a lake reflects the mountains and sky.

Teaching Tip

Students may become frustrated if they feel they cannot match the analog images. Reassure them this is fine. Remind them about the discussion from the warm up and ask if it's possible that digital images ever look exactly like analog images. You may also ask the students if their representation would be improved if they use more bits per pixel.

Wrap Up

Remarks

Prompt: How is an image represented on a computer?

Discussion Goal: Students should understand how sampling, pixels, and binary work together to make a digital approximation of an analog image. They should also understand that while analog images are able to change color values smoothly and continuously, digital images rely on pixels to change from a fixed number of color values discretely using squares of equal size.

Journal: Students record the layers of abstraction in their journals.

Remarks

Assessment: Check for Understanding

Question: Which statement about analog and digital images is true?

Question: Describe how the process of sampling, RGB pixels, and binary sequences work together to display a digital color image.

Standards Alignment