What is jpeg?

JPEG (pronounced “jay-peg”) stands for Joint Photographic Experts Group, the name of the committee that created the standard. It is a common file format used to store digital photos and images. JPEG files compress image data to make the file size smaller, which makes them easy to share and store, but the compression is “lossy,” meaning some image detail is permanently discarded.

Let's break it down

  • Image data: A digital picture is made of millions of tiny squares called pixels, each with its own color information.
  • Compression: JPEG looks for patterns and similarities in groups of pixels and replaces them with simpler data.
  • Lossy vs. lossless: JPEG throws away some color detail to shrink the file (lossy). Other formats like PNG keep every detail (lossless).
  • Quality setting: When you save a JPEG, you can choose a quality level (e.g., 90%, 70%). Higher quality = larger file, lower quality = smaller file but more visible artifacts.

Why does it matter?

Because photos can be huge, sending them over the internet or storing thousands of them would quickly fill up space. JPEG’s compression lets you keep reasonable image quality while using far less storage and bandwidth. This makes it practical for websites, email, social media, and digital cameras.

Where is it used?

  • Digital cameras and smartphones save pictures as JPEG by default.
  • Websites display product images, blog pictures, and galleries in JPEG format.
  • Email attachments and messaging apps often compress photos to JPEG before sending.
  • Social media platforms (Facebook, Instagram, Twitter) automatically convert uploads to JPEG to save space and speed loading.

Good things about it

  • Small file size: Great for fast loading and easy sharing.
  • Widely supported: Almost every device, browser, and program can open JPEGs.
  • Adjustable quality: You can balance size and visual fidelity to suit your needs.
  • Good for photos: Handles complex color gradients and natural scenes well.

Not-so-good things

  • Lossy compression: Repeatedly editing and re‑saving degrades image quality over time.
  • Artifacts: At low quality settings you may see blocky or blurry spots, especially around edges.
  • Not ideal for graphics: Images with sharp lines, text, or limited colors (like logos) look better in lossless formats such as PNG or SVG.
  • Limited color depth: JPEG stores 24‑bit color, which is fine for most photos but not for high‑dynamic‑range (HDR) work.