ios - how to get the result in template matching code? -


i beginner computer vision .i working on project find match between 2 images using matchtemplate in ios.the problem facing finding way determine whether 2 images matching or not although matchtemplate working well.i thought of taking percentage of result matrix did not know how , not find way.also minmaxloc did not work me . if can me or give me idea really appreciate cause on desperate point now. here code: `

uiimage* image1 = [uiimage imagenamed:@"1.png"]; uiimage* image2 = [uiimage imagenamed:@"image002.png"];

// convert uiimage* cv::mat uiimagetomat(image1, matimage1); uiimagetomat(image2, matimage2);   matimage1.resize(100 , 180); matimage2.resize(100 , 180);    if (!matimage1.empty()) {     // convert image grayscale     //we can use bgra2gray : blue , green , red , alpha(opacity)     cv::cvtcolor(matimage1, grayimage1, cv::color_bgra2gray );     cv::cvtcolor(matimage2, grayimage2, cv::color_bgra2gray);   }   /// create result matrix int result_cols =  grayimage1.cols ; int result_rows = grayimage1.rows ;  result.create( result_cols, result_rows, cv_32fc1 );  /// matching , normalize matchtemplate( grayimage1 , grayimage2 , result ,  cv_tm_sqdiff_normed);  //normalize normalize( result, result, 0, 100, cv::norm_minmax, -1 );  //threshold cv::threshold(result , result , 30, 0, cv_thresh_tozero);`

the intent of matchtemplate(...) template smaller image. template moved across image sliding window , 'matching score' calculated in way e.g. using cross-correlation or squared difference.

so if, input image 10x10 , template 3x3, template positioned top left corner @ top left corner of image (centre of template @ pixel (1,1) assuming index 0). matching score calculated , template slides (1,2) , match again. when template's middle pixel @ (8,1) slide down next row (1,2) , repeat.

the output result of process 8x8 matrix value @ each position represents matching score when template @ point. size of output image w-w+1 x h-h+1 wxh size of image , wxh size of template.

you can use minmaxloc work out highest , lowest scores in output matrix and, depending on matching score use, 1 of these match template within image.

now resizing template , image same size: 

matimage1.resize(100 , 180); matimage2.resize(100 , 180);

which means there 1 place template can located within image , output matrix should 1x1 grid.

you using 

cv_tm_sqdiff_normed

which normalised squared difference. score, lower matching score better. i.e. closer value in 1x1 output matrix 0, closer match between template , image.

given sizes of template , image 100x180 can calculate maximum value matching score can have 100x180x255 if entire image black , template white or vice-versa. should work out sensible threshold below t=your template matched image.

since have 1x1 output though there's little value in normalising or thresholding result.


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