Notes

Graphic File Formats

File Formats:

• All computer documents are packaged in different formats
• The file format is determined by the origin (Photoshop=PSD)
• Graphic files (JPG,PNG,GIF) can be reduced in file size by using compression formats

Lossy vs Lossless:

• Graphic image formats fall under 2 categories of compression (Lossy and Lossless)
• Lossy; Image data is “lost” or reduced for smaller file sizes but can result in poor image quality.(pixelation)
• Lossless; Larger files sizes which results in higher quality

Graphic Formats:

• Most common formats are TIF, JPG, GIF
• PNG is common web format; high quality
• Each format has advantages and disadvantages

TIF:

• (Tagged Image File)
• Common for desktop publishing
• Lossless file format
• Cannot display over internet

JPG:

• (Joint Photographers Group)
• Created for digital photography
• Lossy Format
• Can reduce an image file size by 10:1 without showing pixilation
• Level of compression is adjustable

GIF:

• (Graphics Interchange Format)
• Best graphics that have flat color or even tone
• Reduces image by “indexing” color from 3 channels to 1
• Is adjustable by changing color bits from 1 to 8
• Contains no DPI (Dots Per Inch) data for printing. Not a proper format for print

Know Your Pixels:

• TIF and JPg are best for images with pixels that blend in color (Contiguous Pixels)
• GIF is best for images with flat tone (Non-contiguous Pixels)