0
|
2722 Views
|
|
4 Total Likes
View groups...
Share
GROUPS:

# Exame mark table detection

Posted 10 years ago
 Dear Community Exists a way in Mathematica to detect marker fields on an image, see attached draft. The possible marker matrix is always the same only the marked position can vary. For example it means according to the attachment, the first marked field in the first row gives the coordinate/position B1. Many thanks in advanced for your support. Best regards Georg
 Hi,here is something to start with: img = Import["~/Desktop/marker00.jpg"] First we need a grid. If the boxes are more or less in the same position then we can create a template grid; I used the GetCoordinates tool: coords = {{80.5, 321.5}, {78.5, 260.0}, {79.5, 182.5}, {78.5, 115.5}, {80.5, 51.5}, {145.5, 322.5}, {214.5, 322.5}, {281.5, 322.5}, {350.5, 324.5}, {424.5, 323.5}}; Show[img, Graphics[Point /@ coords]] The dots mark my coordinates. This gives me a coordinate grid: Show[img, Graphics@Line[{{Min[coords[[1 ;; 5]][[All, 1]]], #[[2]]}, {Max[ coords[[6 ;;]][[All, 1]]], #[[2]]}}] & /@ coords[[1 ;; 5]], Graphics@Line[{{#, Min[coords[[1 ;; 5]][[All, 2]]]}, {#, Max[coords[[1 ;; 5]][[All, 2]]]}}] & /@ Join[{Min[coords[[1 ;; 5]][[All, 1]]]}, coords[[6 ;;]][[All, 1]]]] I can extract the relevant coordinate for the x- and y-axes: xaxis = Reverse@Join[{Min[coords[[1 ;; 5]][[All, 1]]]}, coords[[6 ;;]][[All, 1]]]; yaxis = Reverse@coords[[1 ;; 5]][[All, 2]]; which I can then use to cut the respective fields out. To get a clearer representation I plot them in a grid: Grid[ArrayReshape[ ImageTrim[img, #] & /@ Reverse@Flatten[ Table[{{xaxis[[i + 1]], yaxis[[j + 1]]}, {xaxis[[i]], yaxis[[j]]}}, {j, 1, Length[yaxis] - 1}, {i, 1, Length[xaxis] - 1}], 1], {4, 5}], Frame -> All] Next, we binaries: Grid[ArrayReshape[ Binarize /@ (ImageTrim[img, #] & /@ Reverse@Flatten[ Table[{{xaxis[[i + 1]], yaxis[[j + 1]]}, {xaxis[[i]], yaxis[[j]]}}, {j, 1, Length[yaxis] - 1}, {i, 1, Length[xaxis] - 1}], 1]), {4, 5}], Frame -> All] and count the pixels: graydata = ArrayReshape[ Total[Flatten[ ImageData[ ColorNegate@#]]] & /@ (Binarize /@ (ImageTrim[img, #] & /@ Reverse@Flatten[ Table[{{xaxis[[i + 1]], yaxis[[j + 1]]}, {xaxis[[i]], yaxis[[j]]}}, {j, 1, Length[yaxis] - 1}, {i, 1, Length[xaxis] - 1}], 1])), {4, 5}]; We can plot this to check: graydata // ArrayPlot There are obviously two clusters: clusts = FindClusters[Flatten[graydata], 2]; Which we can use to attach a "1" to "ticked" and a "0" to "unticked". Flatten[Table[# -> 2. - i & /@ SortBy[clusts, Total][[i]], {i, 1, 2}]] That gives us the matrix we want: Grid[graydata /. Flatten[Table[# -> 2. - i & /@ SortBy[clusts, Total][[i]], {i, 1, 2}]], Frame -> All] Note, that this describes the train of thought. We can wrap everything up into this nice and easily readable function: tickedBoxes[img_Image] := Module[{}, coords = {{80.5, 321.5}, {78.5, 260.0}, {79.5, 182.5}, {78.5, 115.5}, {80.5, 51.5}, {145.5, 322.5}, {214.5, 322.5}, {281.5, 322.5}, {350.5, 324.5}, {424.5, 323.5}}; yaxis = Reverse@coords[[1 ;; 5]][[All, 2]]; xaxis = Reverse@Join[{Min[coords[[1 ;; 5]][[All, 1]]]}, coords[[6 ;;]][[All, 1]]]; graydata = ArrayReshape[Total[Flatten[ImageData[ColorNegate@#]]] & /@ (Binarize /@ (ImageTrim[img, #] & /@ Reverse@Flatten[Table[{{xaxis[[i + 1]], yaxis[[j + 1]]}, {xaxis[[i]], yaxis[[j]]}}, {j, 1, Length[yaxis] - 1}, {i, 1, Length[xaxis] - 1}], 1])),{4, 5}]; clusts = FindClusters[Flatten[graydata], 2]; graydata /. Flatten[Table[# -> 2. - i & /@ SortBy[clusts, Total][[i]], {i, 1, 2}]]] If you throw your image in it should work: tickedBoxes[img] (*{{0., 1., 0., 0., 0.}, {0., 0., 1., 0., 0.}, {0., 1., 0., 0., 0.}, {0., 0., 0., 1., 0.}}*) There is a lot we can improve, but it should be a starting point.Cheers,Marco