Dilation The basic morphological operations applied to either grayscale or binary images are Erosion and Dilation. Erosion shrinks image objects while dilation expands them. Course Name: Digital Image Processing Level(UG/PG): UG Author(s) : Phani Swathi Chitta Mentor: Prof. Saravanan Vijayakumaran *The contents in this ppt are licensed under Creative Commons Attribution-NonCommercial-ShareAlike 2.5 India license

Learning Objectives After interacting with this Learning Object, the learner will be able to: Explain the basic morphological operation (Dilation)

1 2 3 4 5 Definitions of the components/Keywords: Characteristics of Dilation - Dilation generally increases the sizes of objects, filling in holes and broken areas, and connecting areas that are separated by spaces smaller than the size of the structuring element. - With grayscale images, dilation increases the brightness of objects by taking the neighborhood maximum when passing the structuring element over the image. - With binary images, dilation connects areas that are separated by spaces smaller than the structuring element and adds pixels to the perimeter of each image object. The dilation operator takes two pieces of data as inputs. - The first is the image which is to be dilated. - The second is a (usually small) set of coordinate points known as a structuring element (also known as a kernel). It is this structuring element that determines the precise effect of the dilation on the input image. In dilation, every background pixel that is touching an object pixel is changed into an object pixel. Dilation makes the objects larger, and can merge multiple objects into one. 1 2 3 4 5

Master Layout 1 1 Original Image Image after dilation 2 3 Give radio buttons to select any one structuring element of sizes 5x5, 7x7, 11x11 The structuring elements (SE) are 4 5

3 Step 1: 1 2 4 5 Instruction for the animator Text to be displayed in the working area (DT) Show the original image first then show the structuring element selected by the user The text in DT should appear in parallel to the figures The original image The structuring element 5

3 Step 2: 1 2 4 5 Instruction for the animator Text to be displayed in the working area (DT) The SE must move on the original image such that the center of the SE must move pixel by pixel of original image The text in DT should appear in parallel to the figures The left image is the original image The 5

3 Step 3: 1 2 4 5 Instruction for the animator Text to be displayed in the working area (DT) The first fig. should appear and then when the slider points at sigma, the second fig. should be shown The text in DT should appear in parallel to the figures The original image The resulting image after high boost filtering is applied The filter mask used for smoothing is of size 3x3 5

3 Step 4: 1 2 4 5 Instruction for the animator Text to be displayed in the working area (DT) The first fig. should appear and then when the slider points at sigma, the second fig. should be shown The text in DT should appear in parallel to the figures The original image The resulting image after high boost filtering is applied The filter mask used for smoothing is of size 3x3 5

3 Step 6: 1 2 4 5 Instruction for the animator Text to be displayed in the working area (DT) The first fig. should appear and then when the slider points at sigma, the second fig. should be shown The text in DT should appear in parallel to the figures The original image The resulting image after high boost filtering is applied The filter mask used for smoothing is of size 3x3 5

3 Step 7: 1 2 4 5 Instruction for the animator Text to be displayed in the working area (DT) The first fig. should appear and then when the slider points at sigma, the second fig. should be shown The text in DT should appear in parallel to the figures The original image The resulting image after high boost filtering is applied The filter mask used for smoothing is of size 3x3 5

3 Step 8: 1 2 4 5 Instruction for the animator Text to be displayed in the working area (DT) The first fig. should appear and then when the slider points at sigma, the second fig. should be shown The text in DT should appear in parallel to the figures The original image The resulting image after high boost filtering is applied The filter mask used for smoothing is of size 3x3 5

Test your understanding Electrical Engineering Slide 1 Slide 3 Slide 23, 24,25 Slide 26 Introduction Definitions Analogy Test your understanding (questionnaire)‏ Lets Sum up (summary)‏ Want to know more… (Further Reading)‏ Interactivity: Try it yourself Select any one of the figures a b c d Select the structuring element 12 Credits

Questionnaire 1 1.After dilating the image, will the number of background pixels increase or decrease? Answers: a) Increase b) Decrease 2 3 4 5

4 Questionnaire 1 2 3 5 2. Image a Image b:Structuring Element What is the resulting image after dilating the image a using structuring element (image b)? Answers: a) b) 2 3 4 5

4 Questionnaire 1 2 3 5 2. Image a Image b:Structuring Element What is the resulting image after dilating the image a using structuring element (image b)? Answers: c) d) 2 3 4 5

Links for further reading Reference websites: http://siri.lmao.sk/fiit/DSO/Prednasky/2a Morphological processing Recap & Extend / Digital Image Processing Lecture Morphological processing Recap &Extend.pdf http://en.wikipedia.org/wiki/Dilation_%28morphology%29 http://homepages.inf.ed.ac.uk/rbf/HIPR2/dilatedemo.htm http://homepages.inf.ed.ac.uk/rbf/HIPR2/dilate.htm Books: Digital Image Processing – Rafael C. Gonzalez, Richard E. Woods, Third edition, Prentice Hall