Hands-on Activity RGB to Hex Conversion

Learning Objectives

After this activity, students should be able to:

• Find the color of a specific pixel in an image.
• Convert the RGB value of a pixel to hexadecimal.
• Average a pixel's value from surrounding pixels.
• Explain how this information connects to engineering.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

Each student needs:

• calculator
• access to the Internet
• RGB to Hex Conversion Worksheet

Worksheets and Attachments

Pre-Req Knowledge

• A basic understanding of the definitions of digital image, pixel, RGB and hexadecimal.
• Previous exposure to the equations and process used to convert between RGB and hexadecimal.

Introduction/Motivation

Tell me what you know about digital images? What's a pixel? What are we talking about when we say RGB and hexadecimal? What do they have to do with digital images? (Listen to student responses. Correct and amend their understanding, as necessary.)

In this activity, you will practice converting between RGB and hex representations of a pixel value. Then you will explore a website dealing with color and figure out how to find the average value of a pixel from the values of the pixels surrounding it.

Procedure

1. Gather materials, arrange for computer access and make copies of the worksheet.
2. Divide the class into student pairs and hand out the worksheets.
3. Direct student groups to do the conversions between RGB and hex on the worksheet.
4. Then have students go to the the DEW Power of Digital Images website to read about digital images and making colors with light (as opposed to pigment), and summarize on the worksheet what they learned.
5. Next, have students average the pixel values surrounding a central pixel to find the value of the central pixel.
6. As a class, share and discuss students' results and conclusions. Link what they've just done to real-world engineering by explaining that computer science engineers make similar calculations as part of their work.

Vocabulary/Definitions

digital image: An image represented in binary.

hexadecimal: A number system that uses 16 different symbols per placeholder, 0-9 and A-F. The first 30 numbers are: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,10,11,12,13,14,15,16,17,18,19,1A,1B,1C,1D.

pixel: One of the small discrete elements that constitutes a digital image.

Assessment

Pre-Activity: Ask students questions to assess their base knowledge of the background knowledge for this activity, and amend as necessary. Ask the students: What do you know about digital images? What is a pixel? What do RGB and hexadecimal have to do with digital images?

Embedded and Post-Activity/Lesson: Observe students' calculations and answers as they work through the worksheet. At activity end, review their answers to gauge their depth of understanding of the lesson and activity content.

References

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under National Science Foundation RET grant nos. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.