PNG File Format

What is PNG?

PNG (Portable Network Graphics) is a raster graphics file format that uses lossless compression. Developed in 1996 as an alternative to GIF, it has become widely used on the web.

Key Features

  • Lossless compression: Reduces file size without losing image quality
  • Transparency support: Supports full transparency to semi-transparency through alpha channel
  • 24-bit true color: Can display 16.7 million colors
  • Gamma correction: Enables consistent color display across different devices
  • Interlacing: Allows progressive loading of images

Advantages of PNG

  • Perfect for images with sharp edges like text, logos, and icons
  • No quality loss even after repeated editing
  • Full support in web browsers
  • Can store metadata

Disadvantages of PNG

  • Larger file size than JPEG for photographic images
  • No animation support (except APNG)
  • No CMYK color mode support (unsuitable for printing)

PNG File Structure

PNG files consist of the following chunks:

  • IHDR: Image header (width, height, color depth, etc.)
  • PLTE: Palette information (for indexed color images)
  • IDAT: Actual image data
  • IEND: Image end marker

Use Cases

  • Website logos and icons
  • Screenshots
  • Images requiring transparent backgrounds
  • Diagrams and charts
  • Digital art and illustrations