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

Evaluate this tutorial

PDF Handout

 

Resolution

As mentioned in the definition of terms earlier in this tutorial, resolution refers to the sharpness and clarity of your image. Of course, the sharpness and clarity vary depending on the context of the image. Are you scanning or viewing your image? Are you viewing it on a computer monitor, or are you looking at a printed page?  

Scanning: When scanning your images, you are usually prompted to choose what resolution you would like your images scanned at. The intended use or display of your images will help you make this choice.  

Printing: Images intended for high-quality printing should be scanned in at no less than 150dpi, preferably 300dpi. Remember, dpi is "dots per inch", and the more dots per inch, the sharper and crisper your images will look on the printed page. Many publishers have minimum resolution requirements for digital image submissions - make sure you know what's required before you start digitizing.

Computer display: Images intended primarily for display on a computer monitor (such as email attachments or images on a Web page) really only need a 72ppi to 96ppi resolution, as that is what computer monitors are capable of displaying. A higher resolution will not make your image appear any better on the screen. In fact, if you don't expect folks to print out your images, these images should be "optimized", which means making them as small and compressed a file as possible (while still retaining the appropriate visual clarity), so that they load quickly, and do not take up too much space on the hard drive.

TIP - Optimizing images for computer/Web display involves compression, which throws out some pixel data. You cannot then enlarge the optimized images without encountering pixelation (see second example below).

TIP - if you need to make high resolution, large files available via the Web or computer, create "thumbnail" versions of your images that then link to the larger images. This prevents your viewer from enduring slow loading times for images they are not interested in seeing.

Resolution Example(image courtesy of author)

In order to see distinguishable differences in between the low-resolution JPG image below and its high-resolution TIFF counterpart, print the handout (available from the menu on the left)



Ideal for Computer/Web Use

Format:   JPG

DPI: 72

Pixel Dimensions: 361 x 210

Print Dimensions: 5" x 3"

File Size:   222KB

 

Enlarged jpg image with individual pixels visible

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