The Importance of Resolution and Compression

You can print a beautiful 8 x 10 quality print from and image recorded at 1127 x 1704 (4 megapixels) or larger. These photos are quite suitable for framing and display, or even for the cover of a well-known magazine. Being close to the action will even allow you to crop the image and still have quality resolution for a good-sized print.

However, if you want a picture the size of a credit card, use 640 x 480 resolutions, no posters, and not what you want on display at your first showing, but great for camera phones!

If you have a massive enough memory card, there is no reason to shoot at low resolution and chance missing a really great shot! It also allows you to show off your work in a very big way, which should always be a consideration.

When buying your camera, don't fall into the notion that more megapixels are necessarily better; all pixels are not created equal. When items go digital, everyone believes that smaller is better.

But think about this -- pixels used in digital camera sensors are used to record the light in your photos, so doesn't it make sense that larger pixels will record better light?

Carrying this on to its final conclusion, they would also create a better quality digital image. The ability to miniaturize items has led to scientists squeezing more pixels onto an imaging sensor, so they are smaller. What this means is that the sensor is smaller, but the number of pixels stays the same.

The small sensor may be more efficient due to the smaller size; this does not mean it will produce better photos, than larger pixels on a larger sensor. Check the size of the sensor when you are thinking about purchasing a new digital camera.

Digital Image File Compression

Image file compression algorithms come in two types, lossy and lossless:

* Lossless compression reduces the file size with no loss to the quality of the image, even though the compression ratios may be weak. If an image is to be printed or the quality is more important than the file size, lossless algorithms are preferred.

* Lossy compression takes advantage of the limitations of the human eye and discards information that can't be seen. These algorithms allow for variable levels of compression, and as they are compressed, the file size is reduced. The more the file is compressed, the more the image deteriorates and becomes noticeable; this is called artifacting.

The JPEG software incorporates an algorithm Exif (Exchangeable image file) format used in most cameras. This is used to standardize and record the exchange of data between editing and viewing software and the digital camera. Recorded for individual images, the data includes:

* Time and date

* Shutter speed

* Camera settings

* Exposure

* Image size

* Name of camera

* Color information

* Compression

Using image editors to view the pictures, this information can then be displayed.

PNG, JPEG and GIF are the most common file formats used on the Internet. There are two main families of graphics: raster and vector.

JPEG (Joint Photographic Experts Group) image files are of the lossy format. Most digital cameras have the ability to save to a JPEG format (the DOS extension for JPEG is JPG). This format supports 8-bit per color RGB (red, green, and blue) for a 24-bit total, and it creates relatively small files.

In most situations, the compression doesn't distract from the image quality. However, JPEG files do degrade more as they are repeatedly saved, so it is best to store images in a lossless non-JPEG format.