0116136 Computer Vision Introduction to Digital Images.
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Transcript of 0116136 Computer Vision Introduction to Digital Images.
Digital ImagesDigital 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.