How Images Become Numbers
Before we can train any model, we need to first understand what an image actually looks like to a computer.
An image is stored as a grid of pixels. Each pixel encodes the color at that location using three numbers: how much red, how much green, and how much blue. Those values range from 0 to 255. A pure white pixel is [255, 255, 255]. A pure black pixel is [0, 0, 0]. A pale blue-tinted light might read [204, 229, 255].
A standard HD image might be 1080 rows by 1920 columns, with three channels per pixel. That means a single image is a tensor of shape [1080, 1920, 3], containing over six million numbers!
Sample image (16×12 px)
Hover or tap a pixel to inspect it
Pixel inspector
Hover over a pixel
to inspect its values
Tensor shape: [12, 16, 3] — 576 values total
Hover over any pixel in the sample image to see its RGB values. Toggle to grayscale to see how color collapses to a single luminance value per pixel.
A grayscale medical X-ray is 512 × 512 pixels. What shape is its tensor representation, and how many total numbers does it contain?