Facts

• Joint Photographic experts Group
• Lossy compression (not lousy, lossy): Data from original is "lost"
• More compression = less quality, but smaller file size
• Different applications use different numbers to describe compression settings (there is no standard), but generally, a higher number means less compression

• Open-standard
• Very large example file of quality settings
• Excellent article on wikipedia

Usage

• Photographs
• Images with soft edges or color gradients
• It's a challenge to optimize size/compression

jpg set to 80 in photoshop: 14k filesize

jpg set to 0 in photoshop: 2k filesize

Facts

• portable network graphics
• Lossless compression, therefore larger than jpgs
• 8bit, 24bit, 32bit (24bit + 8bit alpha channel)
• 8bit can have 2,4,6,8,16,32,64,128,256 colors
• 8bit can have transparent colors in palette
• Highly flexible data format can hold vector and metadata information
• Fireworks’ native format
• Can be streamed through “interlacing”
• Open-standard

Usage

• Poor choice for photographs – looks great, but file sizes are way bigger than a .jpg
• Better choice for text, solid colors, sharp color transitions
• The only way to get an alpha channel transparency

Facts

• Graphics Interchange Format
• Lossless compression
• 8bit palette (2,4…256 colors)
• Colors in palette can be designated as transparent
• Capable of animation


The original Dancing Hamsters

Facts

• Tagged Image File format
• Not supported on the web
• Owned by Adobe, but available free
• Highly flexible file format can contain compression and vectors

Usage

• Used by scanners and screen-grab
• Used for high-color-depth images (>24bit)

Facts

• Uncompressed
• Supports various bit depths: 1,4,8,16,24, 32
• Supported by Microsoft
• Patent-free

Usage

• Legacy format from MS-DOS and Windows