Class Note for ECE 482 at UA-Comp Visn Dig Image Proc
Class Note for ECE 482 at UA-Comp Visn Dig Image Proc
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This 4 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Alabama - Tuscaloosa taught by a professor in Fall. Since its upload, it has received 18 views.
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Date Created: 02/06/15
Computer Vision amp Digital Image Processing Basic Image Processing Operations aaonca sconomakznoinoonno Dr D J Jackson La urel1 Distance measures Given pixels p q and 2 at xy st and uv respectively D is a distance function or metric if DOW 20 DDoQ0 W DW DOW DWP and DDoZSDDoQ DWI The Euclidean distance between p and q is given by DJPJI wxisy 14Z The pixels having distance less than or equal to some value rfrom xy are the points contained in a disk of radius r centered at xy Eemrica sconomaznonoonno Dr D J Jacison La urelz Distance measures continued The DA distance also called the city block distance between p and q is given by D4pgtq Ixislyitl The pixels having a D4 distance less than some rfrom xy form a diamond centered at xy Example pixels where D4 g 2 2 2 1 2 NotePixels with D41 2 1 0 1 2 are the 4neighbors 2 1 2 ofxy 2 aaonca sconomakznoinoonno Dr D J Jackson La urell Distance measures continued The DE distance also called the chessboard distance between p and q is given by Do Pa 4 maxx SI Iy tI The pixels having a DB distance less than some rfrom xy form a square centered at xy Example pixels where DE g 2 22222 211 12 Note Pixels with D51 2 1 0 1 2 are the 8neighbors 2 1 1 1 2 of xy 22222 Eemrica sconomaznonoonno Dr D J Jacison LectureClA Distance measures and connectivity The DA distance between two points p and q is the shortest 4path between the two points The DE distance between two points p and q is the shortest 8path between the two points 39 D4 and DE may be considered regardless ofwhether a connected path exists between them because the de nition ofthese distances involves only the pixel coordinates For mconnectivity the value of the distance the length of the path between two points depends on the values of the pixels along the path aaonca sconomakznoinoonno Dr D J Jackson La urel Distance measures and mconnectivity P3 PA P1 P2 P Consider the given arrangement ofpixels and assume 7 p Dz and D 1 s p1 and p3 can be 0 0M If V1 and p1 and p3 are 0 the mdistance p p4 is 2 If either p1 or pa are 1 the mdistance p p4 is 3 If p1 and p3 are 1the mdistance p p4 is 4 Eemrica sconomaznonoonno Dr D J Jacison La urels Mconnectivity example 0 1 0 1 1 1 0 1 1 1 1 1 1 1 1 mrdtxmncepp02 mdtstamepp03 mammagppza sigma AcomvmerEnginaering Dr D J Jackson Leciurel7 Arithmetic amp logic operations Arithmetic amp logic operations on images used extensively in most image processing applications 7 May covertne entire image or a subset Arithmetic operation between pixels p and q are de ned as 7 Addition pq Useg urtenreir irnage averaging tn reguee riEIiSE e Subtraction peg Useg urten reir statie backgruund remuvai e Muitipiication pm or pq pxq Usedtu currectgrayrieveishading e DiViSiOi i paMorpq As in rnuitipiieatiein Eemrica AEuNDmaEnginaering Dr D J Jacisun La urel Logic operations Arithmetic operation between pixels p and q are de ned as 7 AND pANDqaiso p q 7 OR pORqaiso pq e COMPLEMENT NOTqaisoq Form a functionally complete set Applicableto binary images Basic tools in binary image processing used for e Masking 7 Feature detection 7 snape anaiysis sigma AcomvmerEnginaering Dr D J Jackson La urela Examples of logic operations A NOTA A B AAND B E A B AORB 39 Eemrica AEuNDmaEnginaering Dr D J Jacisun La urel in Examples of logic operations continued A B Ax0RB I A B NOT A AND B El sigma AcomvmerEnginaering Dr D J Jackson Leciurelii Neighborhoodoriented operations Arithmetic and logical operations may take place on a subset of the image Typically neighborhood oriented Formulated in the context of mask operations also called tempate window or filter operations Basic concept let the value of a pixel be a function of its current gray level and the gray level of its neighbors in some sense Eemrica AEuNDmaEnginaering Dr D J Jacisun La urel i2 Neighborhoodoriented ope rations continued CenSigertnereHeWing subsetuf pixels in an irnage Suppuse We Wanttu filterthe image by iepiaeing the value at Z5Wlth the average value ufthe z Z1 23 pixels in a 3x3 rEngn centered aruund 25 24 ZS 26 F39Erfurman DpEratan unnereinn L 23 2e ZZZi 95242 and assign tn z tneyaiue en Neighborhoodoriented operations continued in the mEIVE general furm the uperatiun may luuk like y 21 24 24 z mwwzn Hue Elm ZA ZS Z6 Tniseguatienis Widelyused in 24 z z irnage preeessing F39ruperselectiun DfEDEf ElEntS Weignts alluvvs fur uperatiuns such as w w2 W3 7 nulsElEducllun W4 W5 W6 7 iegiunininning a edgedelecliun W7 way new a cmpuler Eigmefvg in D J chkmn Ledure 313 zimiicai ampuaiznainenna u D J Jacksm uduezm Sample filtered image Sample filtered image The sample image was ltered using a 3x3 basic high pass lter as follows 71 71 71 l 71 8 71 71 71 71 Result showing highlighted edges in the image The sample image was ltered using a 3x3 basic low pass lter as follows sh i 1 1 1 1 1 1 1 1 1 Result showing ltered image new a cmpuler Eigmefvg in D J chkmn Ledure 315 zimiicai ampuaiznainenna u D J Jacksm Mums Sample filtered image Basic matlab instructions The sample image was ltered using a 5x5 basic low pass lter as follows 1 11 1 25 1 1 Result showing ltered image Sample matlab source les and data les available via website a bmpread m A matlab source le which will load a windows bitmap le into an array 256 color maximum Furmat Ai AllE CMAPi AMEhmpread fllename a cieaies an anay Wiin naine AiNAME in new We pixel data a cieaies a culuvmap Wiin naine CMAFLNAME a bmpwrlte m A matlab source le which will save an arrayto a windows bitmap le 256 color maximum Furmat hmpwr1t9A7NAME magma 39 n1ename39 new a cmpuler Eigmefvg in D J chkmn Ledure 317 zimiicai ampuaiznainenna u D J Jacksm tannele Basic matlab instructions continued colormap CMAPiNAME Use a particular colormap to display an image image AiNAME create and display an image from a given array of data Dr D J Jackson La urella grams a Computer managing
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