Images, Pixels and RGB

Main Ideas

Build Products Around Real Problems

Instagram co-founder Kevin Systrom says he and Mike saw mobile phones as pocket computers and believed sharing images was a promising opportunity. He emphasizes that an app succeeds when it solves a problem people actually have.

How Digital Images Work

A pixel is a tiny element of a digital image. On screens, pixels are made up of red, green, and blue lights. Their combined brightness creates the colors we see, and from a distance, many pixels blend into a complete picture.

Two factors affect how an image looks:

• Resolution describes the number of pixels in an image or screen, often expressed as width by height.
• Pixel density describes how closely pixels are packed. More densely packed pixels can make an image look sharper, even when the overall pixel count is similar.

RGB Values and Binary

Digital images store each pixel’s color as red, green, and blue (RGB) values. Each value ranges from 0 to 255: 0 represents no intensity for that channel, and 255 represents its maximum intensity. For example, turquoise can be represented in decimal as (64, 224, 208).

Computers represent data with bits, each of which is either 0 or 1. Each RGB channel uses 8 bits, or one byte. Eight bits can represent 256 values, from 0 through 255, so a pixel uses 24 bits across its three color channels. The turquoise example can also be written in hexadecimal as 40 E0 D0, a compact alternative to writing its binary values.

Image Filters

A filter can apply a function to each pixel’s RGB values to produce new values. For example, one simple way to darken an image is to subtract a fixed amount—such as 50—from each channel while keeping values from falling below 0. Applying the same transformation across the image changes its overall appearance.

Instagram’s Evolution

Systrom says people initially viewed Instagram as a way to make photos look stylish or retro. It became more significant as a way for people to connect and discover events and movements around the world through images.

Speakers and Sources

• Kevin Systrom — Instagram co-founder; discusses the product’s purpose and its evolution.
• Piper Hanson — Photographer; explains pixels and digital image representation.
• Russell Kirsch — Mentioned as the engineer who scanned a picture of his infant son in 1957; he is discussed, not heard speaking.