Full Name	Progressive JPEG Compression
Compression ID	ImGearCompressions.JPEG = 6
ImageGear Assembly	ImageGear24.Core Assembly
Bit Depth	Gray level: 8, 16 bpp; RGB: 24, 36 bpp; CMYK: 32 bpp; RGB+Alpha: 32 bpp
File Formats	JPEG
IG Platforms Support	WIN32, WIN64, Unix, Unix64, .NET, .NET64, MAC

Comments

Progressive JPEG is considered an extension to the JPEG standard. It produces the same kind of lossy compression as normal JPEG compression (see above), except that it saves multiple copies of the same image using different levels of quality. There is no hard limit on the number of "scans" that may be stored.

When a Progressive JPEG-compressed image is decompressed, the filter decompresses the lowest quality image first. This can be helpful for quickly displaying a version of the image that you are loading. The benefit of this compression is the fast display of an image that is recognizable. The downside is that a JPEG decompression is performed more than once.