Notes on File Formats

NOTES -Graphic File Formats:Understanding format choice and image compression

File Formats-

-all computer documents, or files are packaged in different formats

-the format is determined often by the files origin, such as a software program like Photoshop, or a device like a digital camera

Lossy vs Lossless-

-graphic image formats fall under 2 categories-lossy and lossless

-With lossy, image data is “lost” or reduced for smaller file sizes but can cause poor image quality. Can result in showing “compression artifacts” and shows pixelisation.

-Lossless retains 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 can 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 photo. and works best for photo content

-is a LOSSY format

-can reduce an image file size by 10:1 without showing significant compression artifacts

-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 for print

Know your pixels

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

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

Alias vs Anti-Aliase

-Anti-aliase tries to smooth out jagged edges

-aliased is usually more pixelated and jagged