Image Processing Reference
In-Depth Information
ing noise from images, obtaining the edges of an image and removing details from an image
[ 7 ] .
5.1 Basic Types of Images
There are a total of four basic types of images, namely, binary, grayscale, true color or red-
green-blue (RGB), and indexed. The descriptions of all these images are provided in the fol-
lowing sections.
5.1.1 Binary image
A binary image is a digital image that has only two possible values for each pixel. The pixel is
made up of either in black or white color. Binary images are also called bi-level or two levels.
This means that each pixel can be stored as a single bit in either binary “0” or “1.” Figure 4
shows a binary image.
FIGURE 4 Binary image.
5.1.2 Grayscale image
A grayscale digital image is an image in which the value of each pixel is not the same. The
only colors are shades of gray. Each image pixel is made up of shades of gray from 0 (black)
to 255 (white). Each pixel can be represented by 1 byte or 8 bits. The reason for having such an
image was because less information is needed to be provided for each pixel ( Figure 5 ).
FIGURE 5 Grayscale image.
5.1.3 True color or RGB image
Each pixel will have a particular color that is being described by the amount of red, green, and
blue in it. If each of the components has a range of 0-255, this will give a total of 2 24 diferent
possible colors in an image. Each pixel will require 24 bits and they are called 24-bit color im-
ages ( Figure 6 ) .
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