Converting PNG to JPG reduces file size by applying JPEG lossy compression, trading a small amount of image quality for a significantly smaller output file. PNG uses lossless DEFLATE compression — every pixel is preserved exactly — making PNG files considerably larger than JPEG equivalents, especially for photographs with complex colour gradients. JPEG compresses by grouping pixels into 8x8 blocks and discarding high-frequency detail that the human eye perceives least effectively. At a quality setting of 85-95%, the visual difference from the original PNG is imperceptible for most photographic content. However, images with sharp edges, text overlays, or flat colour regions will show visible JPEG artefacts (blockiness) at lower quality settings. Transparent pixels in PNG are flattened to a solid background colour (white by default) since the JPEG format does not support an alpha transparency channel.