tailieunhanh - Lecture Digital image processing - Lecture 14: Image Enhancement

This chapter presents the following content: The global information of the image with the help of histogram, histogram based techniques, image differencing, averaging of the images, mask processing, linear smoothing operation. | Digital Image Processing CSC331 Image Enhancement 1 Summery of previous lecture The global information of the image with the help of histogram Histogram based techniques, Histogram equalization Histogram specification or also known as histogram matching or histogram modification 2 Todays lecture Image differencing Averaging of the images Mask processing Linear smoothing operation 3 4 5 Dark image 6 Bright Image 7 Low contrast image 8 9 Histogram equalization 10 11 Histogram Specification 12 Histogram equalization and Histogram specification 13 Histogram equalization and Histogram specification 14 Image differencing operation Image differencing taking the difference of pixel values between 2 images 15 Image differencing 16 Averaging of the images Possibility to reduce the noise of the image if the images are of the same scene 17 Image Averaging 18 Mask processing A neighborhood of size more than 1, then the kind of operation that we are going to have that is known as mask processing operation. Linear smoothing operation Nonlinear operation (which is based on the statistical features of the image known as the median filtering operation) The sharpening filter 19 3 by 3 neighborhood around a pixel location (x, y) 20 Mask operation 21 W I,j are also called coefficients Smoothing operation image smoothing is also called the image averaging operation. Is a special filtering operation where the value at a particular location (x, y) in the processed image is the average of all the pixel values in the neighborhood of x and y. So, because it is the average, this is also known as averaging filter and later on we will see that this averaging filter is nothing but a low pass filter. 22 Image smoothing 23 Smoothing spatial filter 24 Smoothing spatial filter Expression 25 Spatial Lowpass Filter 26 Spatial Lowpass Filter 27 Summery of the lecture Image differencing Averaging of the images Mask processing Linear smoothing operation 28 References Prof .P. K. Biswas Department of . | Digital Image Processing CSC331 Image Enhancement 1 Summery of previous lecture The global information of the image with the help of histogram Histogram based techniques, Histogram equalization Histogram specification or also known as histogram matching or histogram modification 2 Todays lecture Image differencing Averaging of the images Mask processing Linear smoothing operation 3 4 5 Dark image 6 Bright Image 7 Low contrast image 8 9 Histogram equalization 10 11 Histogram Specification 12 Histogram equalization and Histogram specification 13 Histogram equalization and Histogram specification 14 Image differencing operation Image differencing taking the difference of pixel values between 2 images 15 Image differencing 16 Averaging of the images Possibility to reduce the noise of the image if the images are of the same scene 17 Image Averaging 18 Mask processing A neighborhood of size more than 1, then the kind of operation that we are going to have that is known as mask processing .