Lossy vs Lossless

Lossy compression achieves dramatic file size reductions (10-20× for JPEG) by permanently discarding image data that the algorithm determines is least important to visual quality. The human visual system is less sensitive to certain types of detail — particularly high-frequency color variations — which lossy compression targets for removal. Once discarded, this data cannot be recovered. Lossless compression preserves every pixel exactly, using mathematical encoding to reduce file size by finding and eliminating redundancy in the data representation. Lossless compression achieves more modest reductions (2-3× for PNG).\n\nPhotography workflow best practices dictate working in lossless formats throughout the editing process. A photographer captures in RAW, processes in TIFF or PNG, and only converts to JPEG as the final export step for web delivery. Each save in a lossy format accumulates additional quality loss (generation loss), so repeated editing and re-saving of JPEG files progressively degrades the image. By staying lossless until the final output, all intermediate edits are applied to full-quality data.\n\nFormat selection depends on the use case. JPEG is standard for web photos and email attachments where file size matters and minor quality loss is acceptable. PNG is used for graphics, screenshots, and images requiring transparency. WebP offers both lossy and lossless modes with better compression than JPEG and PNG respectively. AVIF provides even better compression at the cost of reduced browser support. TIFF is used in professional print workflows where maximum quality is required.\n\nMagic Eraser preserves quality throughout its editing pipeline by processing images at full resolution without intermediate lossy compression. When exporting, users can choose between formats based on their needs — lossless PNG for maximum quality and transparency support, or optimized JPEG or WebP for web-ready delivery at smaller file sizes.