Digital Photography


The quality of the image that a digital camera produces is determined by resolution. Resolution is the amount of detail the camera can capture and is measured by a set of two numbers, where the first number is the number of pixel columns (width) and the second is the number of pixel rows (height),for example as 640 by 480. Another way of referring to resolution is the total number of pixels in the image, typically given as the number of megapixels, which is calculated by multiplying pixel columns by pixel rows and dividing by one million (e.g.2000 X 1500 = 3,000.000 pixels, 3,000.000/1000000 = 3.0 megapixels.

Typical Resolutions
256 X 256 Low resolution 65,000 pixels
640 X 480 Ideal resolution for e-mailing pictures or posting on a web site 307,200 pixels
1280 X 1024 Enough resolution to make sharp prints as large as 4x5 inches.

1,310,720 pixels
1.3 megapixels

1600 X 1200 High resolution, 4x5 inch prints can be obtained at this resolution with the same quality of a photo lab. 1,920.000 pixels
1.9 megapixels
2000 X 1500 Sharp print quality for pintinting 8x10 photos inch and below. 3,000.000 pixels
3.0 megapixels
2350 x 1750 Printed photos with good quality up to 16 x 20 inches 4,112,500 pixels
4.1 megapixels
4064 X 2704 Top of the line. 13 X 9 inch prints can be made with no loss of picture quality. 10,989,056 pixels
11.0 megapixels

Another common way of referring to resolution is in pixels per inch or ppi. For example, an image that hasa pixel dimension of 1600 x 1200 and is 8 inches by 6 inches, will have a resoluton of 200 ppi.

1600 pixels / 8 inches = 200 pixels/inch
1200 pixels / 6 inches = 200 pixels/inch

Since the number of pixels in an image is fixed, increasing the size of an image decreases its resolution and decreasing its size increases its resolution.