Pixel

In simple terms

A pixel (“picture element”) is one tiny dot of colour on a screen. A picture is a grid of pixels. The more pixels there are per inch, the sharper the picture looks.

More detail

A pixel’s colour is stored as numbers — typically three: how much red, green, and blue it has. With 8 bits per channel that’s 256 levels each and about 16.7 million possible colours per pixel. Many displays now use 10 bits per channel (“HDR”) for smoother gradients.

A common pixel layout in memory:

Bytes	Channel
0	Red
1	Green
2	Blue
3	Alpha (opacity)

An “image” is then a width × height grid of these. At 4K (3840 × 2160), that’s just over 8 million pixels per frame; at 60 frames per second it’s half a billion pixels per second. That is why GPUs exist.

Why it matters

Pixels are the unit of digital images — every photo you take, every video you watch, every UI you tap on. Understanding them is the entry point to graphics, compression, and display tech.

Real-world examples

• A 12-megapixel phone camera produces images that are 4032 × 3024 pixels.

• A 4K monitor packs 3840 × 2160 ≈ 8.3 million pixels.

• JPEG and PNG are different ways of compressing those pixels into smaller files.

• A modern smartphone OLED can selectively turn off individual pixels, which is why dark mode genuinely saves battery on those displays (LCD backlighting is always on regardless).

Common misconceptions

• “Pixels are little dots of light on the screen.” They are an abstraction in your image. The actual screen subpixels (red/green/blue stripes) are different from the logical pixels in your file.
• “More megapixels = better camera.” Sensor size, lens quality, and processing usually matter more.

Learn next

How those pixels are stored, compressed, and transmitted — image formats and codecs.