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Introduction to digital images in computer vision. Explore grayscale and color image sensing systems, resolution, quantization levels, image enhancement, and pixel representation. Learn about sampling, quantization, and the properties of digital images.
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0116136Computer Vision IntroductiontoDigitalImages
Digital Images Digital Image: • in general, image is a function of four variables • For color image, λ takes three different values corresponding to red, green and blue components, • For constant λ (black and white), the image function becomes where t is a time variable for a sequence of frames. • For a constant t, f becomes which is a function of two spatial variables.
Digital Image • These values are called “gray levels ”. They are real, non-negative. • Image is of finite size : They are zero outside a finite region, since an optical system has a bounded field of view. • Whenever necessary, we will assume that image functions are analytically well -behaved, e.g. integrable, invertible FT. • After sampling, we have a discrete set of real numbers. (m,n) • After quantization, the resulting quantized gray levels can be regarded as integers f(m,n) • Thus after sampling and quantization, we can assume that a digital image is a rectangular array rectangular array of integer values. • Pixel : An element of a digital image is called a “picture element”. • Binary Image : If there are just two values, e.g. black and white, we usually represent them by 0 and 1.
Except on borders of the array, any point (m,n) has 8 neighbor pixels • Note that diagonal neighbors units away from (m,n) while horizontal and vertical neighbors are only 1 unit away.