Rocket's cousin lives far away and wants to see his new rocket ship drawing. But Rocket can only send numbers.
"How do I send a picture with numbers?" he groans.
Raven draws a grid of squares. She shades some black and leaves some white. "What do you notice about each square?"
"It is either black or white," Rocket says. "Only two choices."
Nova blinks once, then twice. "Here is my hint," she says. "Two choices. Two numbers."
You can send a black and white picture as a grid of numbers.
Each tiny square in the grid is called a pixel. Use 1 for a black pixel and 0 for a white pixel.
Read the grid row by row, from left to right. The person who gets the numbers shades every 1.
Here is a picture sent as numbers. Shade the 1s in your head, or on graph paper.
| Row | Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
|---|---|---|---|---|---|
| 1 | 1 | 1 | 1 | 1 | 1 |
| 2 | 0 | 0 | 1 | 0 | 0 |
| 3 | 0 | 0 | 1 | 0 | 0 |
| 4 | 0 | 0 | 1 | 0 | 0 |
| 5 | 0 | 0 | 1 | 0 | 0 |
Here is a second picture. This one is a face.
| Row | Col 1 | Col 2 | Col 3 | Col 4 | Col 5 |
|---|---|---|---|---|---|
| 1 | 0 | 1 | 0 | 1 | 0 |
| 2 | 0 | 1 | 0 | 1 | 0 |
| 3 | 0 | 0 | 0 | 0 | 0 |
| 4 | 1 | 0 | 0 | 0 | 1 |
| 5 | 0 | 1 | 1 | 1 | 0 |
A 5 by 5 grid has 25 pixels. That is enough for a simple letter or face.
A bigger grid has more pixels, so it can show more detail.
Every pixel still needs a number, so bigger pictures need more numbers.
| Statement | True or false? |
|---|---|
| You read the grid row by row, left to right. | ? |
| A 1 stands for a white pixel. | ? |
| A picture can be sent as numbers. | ? |
You sent pictures with numbers today! Tomorrow we see how phones and computers use the same trick.