1Two things to know first
A picture is a grid, and stamps repeat
You need two small ideas. Watch each one happen:
A picture = a grid of boxes
Every photo is a grid of tiny colored squares called pixels. Saving the picture means writing down one box, then the next, then the next…
Why write the same box twice?
If a row goes blue, blue, blue, blue, you don't have to write "blue" four times. You can write it once and just say "× 4".
2It depends on the picture
Same trick — two very different pictures
A calm row 🟦
Long stretches of one color. The "× lots" trick can fold a whole row into one little tag.
A speckly row
Every box a different color. Nothing repeats, so there's nothing to fold. Keep this in mind…
3Watch the folding happen
Slide it from messy to calm
Here's one row of boxes. Slide toward "calm" and watch matching boxes next to each other snap together into a single "× N" tag — and watch the box-count drop.
Each run of same-colored boxes folds into one tag. Calmer row → fewer tags → smaller file.
4Now race two pictures
Which one shrinks the most? 📦
The phone uses the exact same folding trick on every picture. We'll squeeze two at once: a plain blue sky with a little sun, and a photo of confetti everywhere. Same trick, both at the same time.
Guess before you squeeze
The phone groups together boxes that are the same color. Which picture do you think will shrink the MOST?