Lossy Compression
Lossy compression reduces file size by permanently discarding some image data that the encoder judges least visible to human eyes. JPEG and lossy WEBP are common lossy formats. The process is irreversible: once detail is removed, you cannot restore the original pixels from the compressed file alone. That trade accepts tiny imperfections in smooth gradients or fine textures in exchange for dramatically smaller files suitable for web pages, email, and social sharing.
Quality sliders control how aggressive lossy encoding is. High settings preserve more detail and produce larger files; low settings shrink files faster but may introduce blocky artifacts in skies, noise in shadows, or softness around text. The goal is finding the lowest quality where the image still looks acceptable at its display size—not at full zoom on a monitor.
FileShrinkr applies lossy compression when you export JPG or WEBP with the quality slider, and when you create compressed PDFs from raster images. For photographs destined for screens, lossy formats are usually the right default. Reserve lossless paths when fidelity is mandatory or when you plan further editing from the exported file.