JPG vs PNG: Image Format Differences, Transparency & Compression

- JPG (Joint Photographic Experts Group): Uses lossy compression based on Discrete Cosine Transform (DCT). It discards high-frequency visual information that human eyes are least sensitive to, resulting in dramatically smaller file sizes for photos with subtle gradients and complex colors. - PNG (Portable Network Graphics): Uses lossless DEFLATE compression (similar to ZIP). It preserves every single pixel perfectly without altering color fidelity, making it ideal for screenshots, UI wireframes, digital art, and logos.

The most significant functional difference between the two formats is transparency: - PNG supports a full 8-bit alpha channel (256 levels of transparency), allowing smooth drop shadows, transparent backgrounds, and anti-aliased edges that blend cleanly against any website backdrop. - JPG has zero support for transparency. Any transparent areas saved as JPG are automatically flattened into a solid background color (typically solid white or black).

1. Photographs: JPG produces files 5× to 10× smaller than PNG with imperceptible visual loss. 2. Logos & Typography: Saving high-contrast text or geometric logos as JPG introduces visible "mosquito noise" artifacts around sharp edges while producing larger files than PNG-8 or SVG. 3. Screenshots & UI: PNG yields crystal-clear text readability without color smudging.