Pixels
Pixels
What is a Pixel?
Short for Picture Element, a pixel is the smallest single component of an image.
Pixels are usually arranged in rows and columns and together produce an image.
An image with a portion greatly enlarged.
The individual pixels are seen as squares in the enlarged image.
Computer Monitors
The early computer monitors used to show a display of 640 pixels wide
and 480 pixels high. As technology advanced, the size of the monitors
and the number of pixels that could be shown increased. Now monitors
can show displays of over 1600 x 1200 pixels. Also they can
vary the number of pixels shown on the same screen size.
Digital Cameras
A megapixel is 1 million pixels, and is a term used not only for the number of pixels in an image,
but also to express the number of image sensor elements in a digital camera.
For example, a "640 x 480" graphic image, is 640 pixels wide and 480 high and therefore has a
total number of 640 x 480 = 307,200 pixels or 0.3 megapixels.
A camera with an array of 2048 x 1536 sensor elements (2048 x 1536 = 3,145,728) is commonly said
to have "3.1 megapixels"
How Do Pixels Show Color?
Each pixel can represent a separate distinct colour depending on the number of bits used
to represent each pixel (bits per pixel or bpp).
8 bpp = 2 to the power 8 = 256 colors
16 bpp = 2 to the power 16 = 65,536 colors
24 bpp = 2 to the power 24 = 16,777,216 colors
| In a monochrome image with 8bpp, zero usually represents black and 255 for white, so we can have 256 shades of grey. |
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| A 24-bit depth in a color image allows each pixel 8 bits per red, 8 bits per green and 8 bits per blue so there can be 256 shades of red, 256 shades of green and 256 shades of blue with an overall 16,777,216 colors possible. |  Shades of Red |
 Shades of Green |
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 Shades of Blue |
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