Graphic File Formats
Understanding Format
Choice & Image
Compression
File Formats:
- All computer documents or files are packaged in different formats
- The format is often determined by the file's origin, such as a software program like photoshop or a device such as a digital camera
- Graphic files such as photos, videos, or artwork can be reduced in file size by using image compression formats
Lossy vs. Lossless:
- Graphic image formats fall under 2 categories
- Lossy:
- image data is “lost” or reduced for smaller file sizes but can cause poor image quality - can result in showing “compression artifacts”
- JPG, GIF, JPEG200, JFIF
- Lossless:
- Retains image data for higher quality but larger file sizes
- PICT, TIFF, PSD.AI
Graphic Formats:
- TIF, JPG, & GIF are 3 most common formats for common activities such as printing, scanning, & displaying images over internet
- PNG: common web format is high quality and can contain an alpha (transparency) channel
- Each format has its own advantages & disadvantages
File Format: TIF
- Stands for Tagged Image Format
- Common format for desktop, publishing, print, photo, & graphic design
- Is lossless file format, retains image data for maximum image quality
- Can result in larger file sizes, not fit for display over internet - not browser compatible
File Format: JPG
- Stands for Joint Photographics Expert Group
- Created for digital photography & works best for photo content
- Lossy
- Can reduce an image file size by 10:1 w/o showing significant compression artifacts
- Level of compression is adjustable
- Not for flat graphics
File Format: GIF
- Graphics Interchange Format
- Is best for graphics or images that have flat color or even tone, such as a cartoon
- Reduces image size by “indexing” color from 3 channels to 1
- Is adjustable by changing color bit levels from 1 to 8
- Contains no DPI (Dots Per Inch) data for printing - Not a proper format for print
Web → RGB: JPG, GIF, PNG, SVA
Print → CMYK: TIFF, PICT, BMP.AI, .PSD
- GIFs can be animated/ have frames → “cinemagraphs”
Know Your Pixels
- TIF & JPG are best for images w/ pixels that blend in color, “contiguous pixels”
- GIF is best for images w/ flat even tone, or “non-contiguous pixels”
Alias → 80’s animations, not smooth
Vs.
Anti-Alias → smooth, blended
