Image Quality
A composite measure of visual fidelity encompassing resolution, color depth, compression level, noise, and sharpness.
Image quality describes how faithfully and clearly an image reproduces its subject. Objective metrics include PSNR (Peak Signal-to-Noise Ratio), SSIM (Structural Similarity Index), and VMAF (Video Multimethod Assessment Fusion). Subjective evaluation uses MOS (Mean Opinion Score) based on human perception.
Key determinants are resolution (pixel count), color depth (tonal precision), compression quality (JPEG Q parameter), noise level, and sharpness. These factors trade off against each other: higher compression reduces file size but degrades quality.
For web delivery, the practical challenge is identifying the minimum acceptable quality that minimizes file size. The image compression tool lets you adjust quality parameters with real-time preview, helping find the optimal balance between size and fidelity.