JPEG Image
JPEG (Joint Photographic Experts Group) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality.
History & Origin
The JPEG standard was released in 1992 by the Joint Photographic Experts Group. It quickly became the dominant format for digital photography and the web due to its efficient compression algorithm, which made it possible to store high-quality images in relatively small files.
Internal Structure
JPEG uses a lossy compression algorithm based on the discrete cosine transform (DCT). It divides the image into 8x8 blocks and converts them into frequency-domain representation, discarding high-frequency information that the human eye is less sensitive to.
Advantages
- High compression ratio: Significantly reduces file size.
- Wide compatibility: Supported by virtually every image viewer and browser.
- Full color support: Supports 24-bit color (16.7 million colors).
Disadvantages
- Lossy compression: Quality is lost every time the file is saved.
- No transparency: Does not support transparent backgrounds (unlike PNG).
- Artifacts: High compression can introduce blocky artifacts.