Color Spaces and Color depth
Color Spaces
Color
spaces are different types of color modes, used in image processing .
it is a specific organization of colors.
Some of the common color spaces are:
- RGB
- HSV
- CMY’K
- Y’UV
- YIQ
- Y’CbCr
RGB is
the most widely used color space especially in computer vision field so we will explain it in this article .
Color model RGB
RGB is used
in your TV and computer screens, and hence on web pages
each color
image is actually formed of three different images. Red image, Blue image, and
black image.
[ R=red -- G=green -- B=blue ] (source)
And every
color have scale or range from 0 to 255 .
So if we have
image like this(only black image) :
That’s mean the
value of red color in this image is 0 and the value of green color in this
image is 0 and the value of green color is also 0 .
rgb = (0 , 0 ,0) -- so the result was a black image .
*********************
And if the
image is like this (only red image)
That’s mean rgb
= (255 , 0 ,0)
*********************
And if the
image is like this (only green image)
That’s mean rgb
= (0 , 255 ,0)
And the blue
image is the same concept with rgb = (0 , 0 ,255) and the white image is the same concept
with rgb = (255 , 255 ,255)
Therefore, based on the previous article we conclude that each pixel in the picture has its own characteristics and color and it is now possible to represent this color using RGB System
finally, the color image matrix = red matrix + blue matrix + green matrix
Gray scale image
greyscale image is one in which the value of each pixel is a single sample representing only an amount of light,
also, it carries only intensity information.
Images of this sort, also known as black-and-white or gray monochrome.
A normal
gray scale image can be defined by only one matrix
RGB images are composed
of three independent channels for red, green and blue but grayscale images have
only one channel with only two colors: black and white (also called bilevel
or binary
images)
256 different intensity values for each primary color(source)
Color depth
Color depth also known as bit depth, is the number of bits used to indicate the color of a single pixel.
bit depth specifies the number of bits used for each color component of a single pixel.
A bit is the unit of storage in a digital computer. There are only two numeric values that can be stored in a single bit: 0 and 1. A ’0’ bit represents the number zero, and a ’1’ bit represents the number one.
For example, the number 100101 in binary represents the number 37 in decimal (decimal is the number system that we use in everyday life, while binary is the number system used internally by computers).
This image show how to convert from bits to decimal
To represent numbers greater than one in binary system, we need to use multiple bits in combination. For a given number of bits, say (8-bit), there is a smallest number that can be represented, and a largest number that can be represented.
The smallest 8-bit binary number (used Alot for representing colors) is 00000000, which represents zero, while the largest is 11111111, which represents 255
(256 different intensity values for every channel )
So if we increase the color depth that’s mean the pixel will have more levels of colors to every channel and this enhance the image accuracy .
Comparison: same image on five different color depths (bits)
The following table illustrates different image types in terms of bits (bit depth), total colors available, and common names.
I hope
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a work flaw in understanding the basics as much as possible.
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Thanks.
References /
https://en.wikipedia.org/wiki/Color_depth
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