Screens and Resolution

Resolution is how many pixels wide and tall an image or screen has. You might see 1920 by 1080, called Full HD, meaning 1920 columns and 1080 rows.

Multiply width by height to get total pixels. A twelve megapixel photo has roughly twelve million pixels, often enough for sharp prints at school poster size.

In the pixel grid lab, draw the same smiley on a small grid and a large grid. The small one looks chunky when blown up.

Your phone screen has a fixed resolution. If a photo has more pixels than the screen, the phone downsamples, showing a smaller version that still looks sharp.

If a photo has fewer pixels than the screen and you stretch it full width, each pixel grows into a visible square. That is why old small images look blurry on new big phones.

Video games balance resolution and speed. Lower resolution means fewer pixels to draw each frame, which can run smoother on older hardware.

For class slides, huge twenty megapixel photos slow loading without helping on a projector. Resize exports to what the screen needs.

Aspect ratio is shape: widescreen is wider than tall. Cropping changes which pixels stay, not just their size.

Next you will see that sound is also stored as long lists of numbers sampled thousands of times per second.