PC Tutor Times
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Winter 2002, Volume IV, Issue 1, Page 3 |
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(Note: Links valid at time of first publication may not be valid today.) Happy New Year Digital Photography Reference Winter Olympics (Feb. 8-24) International Olympic Committee Monthly Tools PC
Tutor Web Site Past Newsletters
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Resolution, Megapixels, Compression and Image Quality vs. File Size Resolution and MegapixelsResolution is a term used in graphics to measure the dots-per-inch of a picture. Each dot is called a pixel. A megapixel is a million pixels. The more dots-per-inch the high the resolution. The higher the resolution the larger you can print a picture before you start to actually see the pixels that make up the photo. On the down side, the higher the resolution the larger the picture file will be and therefore the less pictures you can store on a memory card.
Below are two links you can click on to see examples of the same picture in two different resolutions. (Note: If you look at the pictures use your Browser's Back button to return to this page.) The first picture was taken at a 2048 x 1536 pixel resolution. Notice how large the picture is without being able to see the pixels that make up the picture. Picture #1 (File size is 388KB) The second picture was taken at a 1024 x 768 pixel resolution. If you look closely you can see that the picture is smaller and you can already see the pixels that make up the picture. Picture #2 (File size is 92KB) You may be wondering why you see some blurriness. That is because I used compression to reduce the file size. If I hadn't the file would be too large to transfer over the Internet. As it is these file sizes take a long time to download if you don't have a cable modem or DSL. CompressionIf you want to store more pictures on your memory cards or if you want to send your pictures over the Internet via e-mail or a web site then you will have to compress the file. If on the other hand you only want to print your picture then compressing it would degrade the printed quality. Everything about computers is a trade-off and digital photography is no exception.
Tip: If you would like to be able to print high quality prints always take your pictures in high resolution. You can always reduce the file size later with an image editing program. JPEG, Joint Photographic Experts Group, is the preferred method of compression for the Internet. If you receive a file with the last three letters of .JPG then you know it is a picture file and it has been compressed for the Internet. Some digital cameras will save pictures automatically in JPG, but with others you will need to use an imaging editing program. Page 3 of 6 |
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