public save(file as String, quality as Int = 92, background as Int = 0xffffff) as Void
Atomically exports PNG, JPEG, GIF, BMP or TIFF, selected by extension. JPEG/BMP flatten alpha against 0xRRGGBB background (white by default). GIF is a single frame with binary alpha and up to 256 palette colors. TIFF is a single 8-bit RGBA page. Quality (1..100) affects JPEG only. Throws IOException on missing codec/write failure; old file survives. Example: image.save("photo.jpg", quality=92, background=0xffffff).