Subburao's Blog

Digital Image Processing

A digital image processing basically occurs when an analog signal gets converted into a digital format… It is similar to the human vision and how the eye coverts the received rays reflected from the object back to the object…

Now let us see what is a PIXEL… A pixel is the unit of measurement of resolution or clarity of a picture… Any picture taken in a digital cam or a mobile is made up finer cells called Pixels… The smaller and finer and more in number the pixels,the better is the quality of the picture… This is similar to the human body which is made of infinite number of minute cells… If our cells we larger in size and fewer in number we would resemble an amoeba…

Each Pixel is represented by a quantity F(x,y)… where F is the amplitude of the pixel(in other words the size or length of the pixel or a measure of how big it is) and the x,y represents the spatial co-ordinates(in other words all pictures are 2 dimension and they are represented graphically as x and y)

As told before… any image has to be converted to digital from analog in order to process it… therefore, in order to convert to digital we perform the basic SAMPLING AND QUANTISATION….Both the components F-amplitude and x,y-spatial co ordinates have to be digitized… therefore…Digitization of co ordinates is referred as Image Sampling and Digitization of Amplitude is called Image Quantisation…

Sampling is the process of dividing a complete analog signal into smaller signals
Quantisation is the actual process of Analog to Digital Conversion

A Black and white Picture has varying levels of Black,grey and white which is measured by the GREY LEVEL… which assignes a scale from 0 to 255 :
0 – BLACK
255-WHITE