Graphic File Formats

Graphic File Formats

• All computer documents, or files, are packaged in different formats

• The format is determined often by the file origin, such as a software program like photoshop, or a device such as a digital camera

• Graphic files such as a photo, video or artwork can be reduced in file size by using image compression formats

Lossy vs Lossless

• Graphic image formas fall under 2 categories of compression, lossy and lossless

• With lossy, image data is “lost’ or reduced for smaller files sizes but can cause poor image quality. Can result in showing “compression artifacts”

• Lossless retains the image data for higher quality, but larger file sizes

Graphic Formats

• TIF, JPG, and GIF are the 3 most common formats for common activities such as printing, scanning, and displaying images over the internet

• PNG is a common web format, is high quality and contain an alpha (transparency) channel

• Each format has its own advantages and disadvantages

File Format:Tif

• Stands for tagged image format

• Common format for desktop publishing, print, photo, and graphic design

• Is a LOSSLESS file format. It retains image data for maximum image quality

• Can result in larger file sizes, not fit for display over internet, is not browser compatible

File Format:JPG

• Stands for joint photographers expert group

• Created for digital photography and works best for photo content

• Is a LOSSy format

• Ca reduce file image size by 10:1 without showing significant compression artifacts

• The level of compression is adjustable

File Format:GIF

• Stands for 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 to print.

Know Your Pixels

• TIF and JPG are best for images with pixels that blend in color, these are called “contiguous pictures”+

• GIF is best for images with flat even tone, or “non contiguous pixels”