How computers 'see' colour

Computers seem smart but are they really? Find out how they need to be taught something as simple as how to tell if a tomato is ripe.

We are smarter than computers. We can easily tell the difference between ripe and unripe fruit, but computers can’t. Learn how computers can be taught to identify colours and use this ability to check fruit for ripeness. These slides will provide all the resources you need to run this topic with your class. To get the most out of this resource it would be good to first watch this video on the significance of digital technologies.

The significance of digital technologies

In this video Tim Bell shows how numbers are hidden behind digital images. To get the most out of this resource it is good to watch this video first.

Why a Robot Could Happily Eat an Unripe Tomato

Sound of burning fire in the background

Text on screen: Kia Takatu a-Matihiko Digital Readiness - Why a Robot Could Happily Eat an Unripe Tomato Years 5 and 6.

Karl Summerfield and Joanne Roberts, Facilitators, voiceover while viewing slides on screen.

Kia ora koutou, I’m Karl and this is Joanne.

Karl: We designed this slide deck to include everything a teacher would need to teach from. Whether they are doing it face-to-face or in an online format. We envisage teachers literally cutting from our presentation and pasting into their teacher and student communication tool.

We’ve included two videos to give your students a real world context and set the scene for the following activities. Both videos focus on the same Hawkes Bay apple orchard but highlight different aspects of the robotic harvesting.

We’ve focused on tomatoes rather than apples as tomatoes have a clearer colour distinction than apples as to when they are ripe i.e. red is ripe, green is unripe, while some apples are green when they’re ripe and others red.

We’ve also included a written introduction to the topic and then we get into the actual lesson information.

This video here shows the two interactives which are key to these lessons, the ‘Pixel Viewer’ and the ‘RGB mixer’. Both are from the CS Field Guide and are easy to use although you may need to explore these with your students before expecting them to be able to use them independently.

Joanne: We’ve included possible student activities to familiarise students with these interactives. Don’t worry, we’ve also included possible answers to these activities at the end of the slide show.

We’ve also included the computational thinking progress outcomes these activities relate to. Remember, you need to be explicitly teaching these points, not hoping the students pick them up by themselves. These activities have the students being users of technology rather than the creators we aim them to be.

From here in session 2, we start supporting our students to become creators of technology rather than users. We pick up the idea of algorithms, step-by-step processes computers can follow. Starting with those us humans use and then working out how we could break those processes down so a computer could follow them.

When the students write their own algorithms, whether they be for humans or computers to follow, they are beginning to be creators of digital technologies.

Karl: We start with flow charts and introduce the idea of greater than (>) and less than (<). Don’t worry if your students aren’t familiar with these terms, we’ve included resources here you can use to teach these concepts.

In the session 3 section, we take what we’ve learnt in the previous two sections and really become creators of digital technologies.

We explain how to take your flow charts or step-by-step instructions from the previous section and turn them into a simple computer program using Scratch as the programming language. Don’t worry if you’ve never used Scratch before, we’ve included resources to support those of you who are new to Scratch. These resources are also suitable to support your students in learning how to use Scratch.

Joanne: We’ve also included a possible way of solving the problem in Scratch and a link to a Parsons problem which has all the blocks you need to make the program ready for you to assemble. You are welcome to join our online discussion that can be found by typing 'tomato' into the search bar of the Kia Takatū website.

Thank you for your time, we hope you have as much fun sharing this project with your students as we did creating it.

Sound of burning fire in the background.

Text on screen: Kia Takatu a-Matihiko Digital Readiness.

How to use this resource

To fully access this resource, you and your students should have a digital device with internet access. This resource has been created so teachers can copy parts of it into other formats as they require to share with students. It has been split into three sessions but we expect it to take longer than this with students.

To use this resource effectively, you should have access to the following resources:

If any of these links do not work, try opening them in a different browser such as:

Ngā Kiriahi

Share your experience of using this resource with other teachers in the Ngā Kiriahi discussion.

Additional resources

NZ Herald article with a two minute setting-the-scene video. Includes a great explanation of the robotic process.

Robotic apple harvesting

Turners & Growers video of robotic apple harvesting. Includes excellent view of apples being picked by the robot. (34 seconds)

Choose a colour, click on the swatch and find out the RGB values.

Choose a colour, click on ‘more info’ and find out the RGB values.

Point an iPhone or iPad camera at something and see the RGB value and colour name of it.

Play with sliders to mix red, green and blue into new colours. Take a photo and explore the RGB values of each pixel.