digital image processing
Post on 25-Jul-2015
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Digital IMAGE PROCESSING
Amir Hossain13-23814-1
What is a image???
What is a Digital Image???
Digital Image
DIGITAL IMAGES are electronic snapshots taken of a scene or scanned from documents, such as photographs, manuscripts, printed texts, and artwork. The digital image is sampled and mapped as a grid of dots or picture elements (pixels).
Our vs Computer vison
Let’s go to the image root(Continue)
pixel
• A pixel (abbr. for picture element) is the smallest unit of an image.
Let’s go to the image root(Continue)
• MATLAB (Matrix Laboratory) stores images as matrices.
• In MATLAB, image pixels are referenced using (row, col) values.
• Origin of the coordinate system (1,1) is the top left corner of the image
Let’s go to the image root
0.204.102 00000000 11001100 1100110
Image are two kinds:• Grayscale/Black-white image(16 bit image)Such as 11001100 1100110 Black white• RGB/Color image(24 bit image)Such as 00000000 11001100 1100110
Red(R) Green(G) Blue(B)
• Therefore, a 640x480 image is a matrix of 640 columns and 480 rows, each element of this matrix is called an image pixel.
In a summary
• Digital Image is nothing but collection of pixels which are arrange in matrix form
• Pixel is consists of sub pixels(black and white sub pixels for grayscale and red, blue and green sub pixels for color image)
• This sub pixels have value which represented in 8 bits binary number
What is Digital Image processing?
• Digital image processing is the is a method to convert an digital Image in order to get an enhanced image or to extract some useful information from it by using computer algorithms
Some Applications of image processing
Smoothing Image(Gaussian blur method)1/9
1/91/9
1/91/9
1/9
1/91/9
1/9
Origin x
y Image f (x, y)
e = 1/9*106 + 1/9*104 + 1/9*100 + 1/9*108 + 1/9*99 + 1/9*98 + 1/9*95 + 1/9*90 + 1/9*85
= 98.3333
FilterSimple 3*3
Neighbourhood106
104
99
95
100 108
98
90 85
1/91/9
1/9
1/91/9
1/9
1/91/9
1/9
3*3 SmoothingFilter
104 100 108
99 106 98
95 90 85
Original Image Pixels
*
The above is repeated for every pixel in the original image to generate the smoothed image
Image Smoothing Example
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Normal Image
Image Smoothing Example
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Using 3*3 filter
Image Smoothing Example
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Using 5*5 filter
Image Smoothing Example
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Using 9*9 filter
Image Compression(Delta Encoding)
Process of delta encoding• Instate of every pixel value we consider group of
pixels where nearby pixels are most similar
• We give value according to similarity which called delta value• If neighbor pixels are identical then delta value=0
Image Compression(Delta Encoding) Continue
• If almost identical then close to 0 • In a high regulation image neighbor pixels are a
lot more identical so the delta value looks like this
• If we consider this • We can express the group of pixel like this• Png image follow this Encoding which is
lossless compression
Viola Jones face detection
Step 1:Haar feature(collect raw face identifier)
Step 2: Integral Image (specific value for identifier)
Integral Image(continue)
Step 3:Adaboost(find necessary information)
Step 4:Cascading(detect face by matching information)
Summary
Detected Image using Viola Jones
Thank YouAny Questions
???
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