Digital Imaging Basics
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Definitions of Terms

File Formats

Image Production

Image Size

Best Practices

Viewing File Info

Editing Images

File Management

Additional Resources

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File Size

File size is proportional to the pixel dimensions of an image, is partially determined by the file format, and it specifically refers to how much disk space your file occupies, either on the hard drive, CD, or other storage medium.  

Image files normally range in sizes measured in Kilobytes (KB or K) and Megabytes (MB or M); extremely large files may be measure in Gigabytes (GB). Images for print will have larger file sizes, since higher resolution = more data stored in the file.   Images for Web or computer display will have smaller file sizes.  

As a general rule (and there are appropriate times and places to break it), Web images should fall between 10 and 200K; images with larger file sizes will load more slowly, and generally be too cumbersome for effective computer distribution and display.   

Saving your images in .JPG or .GIF format will automatically compress and reduce your file sizes significantly, so that you can fit more files onto a disk or attach more to an email message, without exceeding the disk storage or file size limits.

Inserting images into presentations or other documents:
Resizing images on the screen after inserting them into your PowerPoint presentation or Word document does *not* reduce the file size of that image; this only changes the dimensional display size of the image in that document. Presentations and other documents that contain numerous images can become very large in total cumulative file size. In order to keep such presentation and document files at a reasonable size, you should appropriately resize your image files in an image editor before inserting them into your final document.

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