Digital Imaging Basics
Computing Resources >> Tutorials >> Graphics & Multimedia >> Digital Imaging Basics

Introduction

Definitions of Terms

File Formats

Image Production

Image Size

Best Practices

Viewing File Info

Editing Images

File Management

Additional Resources

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Explanation of File Formats

It is also helpful to understand the common image file formats of digital images, how these file formats differ, and what their recommended use is.

TIFF (.tif), JPG (.jpg, .jpeg), GIF (.gif) and PNG (.png) are file formats (and their respective file extensions) that you are likely to encounter.   Other image file formats are used to a lesser extent; these formats are often proprietary, such as Photoshop .psd files.

TIFF

A lossless file format that can be compressed.   This format is widely supported across operating systems. TIFF is the best file format for archiving high quality images.

JPG or JPEG

The JPG file format was specifically created for photographs, and can contain millions of colors.   JPGs are automatically compressed (you can choose the level of compression to match your desired image quality), resulting in a relatively small file size while still retaining quality.   For this reason, JPGs are ideal for email and Web use. JPGs are lossy, discarding information each time that they are compressed.

GIF

The lossless and compressed file format that is preferred for graphics, because it keeps edges and lines sharp. GIFs are limited to 256 or fewer colors, and are not recommended for photographs, but rather for images with flat fields of color, such as clip art. GIFs can be static or animated.

PNG

Portable Network Graphics format, an open source substitute for GIFs.   PNGs provide a higher lossless compression rate than GIFs, and help to reduce cross-platform differences in image display quality, among other technical advantages. PNG provides a useful format for the storage of images during intermediate stages of editing.   See http://www.libpng.org/pub/png/ for more info.

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