Histogram now takes multiple dimensions

examples/calc-hist.js

@@ -9,19 +9,59 @@ cv.readImage('./files/car1.jpg', function(err, im) {
 
   var bgrPlanes = im.split();
 
-  var size = 4,
+  var size = 256,
       range = [0, 256],
       uniform = true,
       accumulate = true,
-      histFile = 'files/chart.png';
+      histFile = 'files/chart2.png';
 
 
   /// Compute the histograms:
-  var bHist = cv.histogram.calcHist( bgrPlanes[0], size, range, uniform, accumulate );
+  var hist64 = cv.histogram.calcHist( im, [0, 1, 2], [4, 4, 4], [[0, 256], [0, 256], [0, 256]], uniform, accumulate );
-  var gHist = cv.histogram.calcHist( bgrPlanes[1], size, range, uniform, accumulate );
-  var rHist = cv.histogram.calcHist( bgrPlanes[2], size, range, uniform, accumulate );
-
-  console.log("Histograms are \n Blue : ", bHist, "\n Green : ", gHist, "\n Red : ", rHist);
 
+  var bHist = cv.histogram.calcHist( im, [0], [size], [range], uniform, accumulate );
+  var gHist = cv.histogram.calcHist( im, [1], [size], [range], uniform, accumulate );
+  var rHist = cv.histogram.calcHist( im, [2], [size], [range], uniform, accumulate );
 
+//////
+//  Uncommentand run `npm install chartjs-node` to draw the histogram !
+///
+/*
+  var ChartjsNode = require('chartjs-node');
+  var chartNode = new ChartjsNode(1200, 1200);
+  chartNode.drawChart({
+      type: 'bar',
+      data: {
+        labels: bHist.map(function(a,i){return i.toString()}),
+        datasets : [{
+          data : bHist,
+          backgroundColor : "#4183c4",
+          borderColor : "#0c4b8a",
+          label : 'Blue'
+        },{
+          data : gHist,
+          backgroundColor : "#83c441",
+          borderColor : "#0c4b8a",
+          label : 'Green'
+        },{
+          data : rHist,
+          backgroundColor : "#c44183",
+          borderColor : "#0c4b8a",
+          label : 'Red'
+        }]
+      },
+      options: {
+        title: {
+            display: true,
+            text: 'RGB Histograms'
+        }
+      }
+  }).then(function(){
+    return chartNode.writeImageToFile('image/png', histFile);
+  }).then(function(){
+    console.log("result has been written in "+histFile)
+  }).catch(function(e){
+    console.log("error",e)
+  });
+*/
 });

src/Histogram.cc

@@ -20,43 +20,102 @@ NAN_METHOD(Histogram::CalcHist) {
     Matrix* m0 = Nan::ObjectWrap::Unwrap<Matrix>(info[0]->ToObject());
     cv::Mat inputImage = m0->mat;
 
-    // Arg 1 is histogram sizes in first dimension
+    //int dims = 3;
-    /// Establish the number of bins
+    // Arg 1 is the channel
-    int histSize = info[1]->IntegerValue();
+    Local<Array> nodeChannels = Local<Array>::Cast(info[1]->ToObject());
-
+    const unsigned int dims = nodeChannels->Length();
-    // Arg 2 is array of the histogram bin boundaries in each dimension
+    int channels[dims];
-
+    for (unsigned int i = 0; i < dims; i++) {
-    Local<Array> nodeRange = Local<Array>::Cast(info[2]->ToObject());
+      channels[i] = nodeChannels->Get(i)->IntegerValue();
-    unsigned int num_range = nodeRange->Length();
-
-    /// Set the ranges ( for B,G,R) )
-    float range[num_range];
-    for (unsigned int i = 0; i < num_range; i++) {
-      range[i] = nodeRange->Get(i)->NumberValue();
     }
-    const float* histRange = { range };
 
-    // Arg 3 is uniform flag
+    //int channels[] = {0, 1, 2};
-    bool uniform = info[3]->BooleanValue();
 
-    // Arg 4 is accumulate flag
+    // Arg 2 is histogram sizes in each dimension
-    bool accumulate = info[4]->BooleanValue();
+    Local<Array> nodeHistSizes = Local<Array>::Cast(info[2]->ToObject());
+    int histSize[dims];
+    for (unsigned int i = 0; i < dims; i++) {
+      histSize[i] = nodeHistSizes->Get(i)->IntegerValue();
+    }
 
+    // Arg 3 is array of the histogram bin boundaries in each dimension
+
+    Local<Array> nodeRanges = Local<Array>::Cast(info[3]->ToObject());
+    /// Set the ranges ( for B,G,R) )
+    float histRanges[dims][2];
+
+    for (unsigned int i = 0; i < dims; i++) {
+      Local<Array> nodeRange = Local<Array>::Cast(nodeRanges->Get(i)->ToObject());
+      float lower = nodeRange->Get(0)->NumberValue();
+      float higher = nodeRange->Get(1)->NumberValue();
+      histRanges[i][0] = lower;
+      histRanges[i][1] = higher;
+    }
+
+    float first_range[] = { histRanges[0][0], histRanges[0][1] };
+    float second_range[] = { 0, 0};
+    float third_range[] = { 0, 0};
+
+    if(dims >= 2){
+      second_range[0] = histRanges[1][0];
+      second_range[1] = histRanges[1][1];
+    }
+    if(dims >= 3){
+      third_range[0] = histRanges[2][0];
+      third_range[1] = histRanges[2][1];
+    }
+
+    const float* histRanges1[] = {first_range, second_range, third_range};
+
+    // Arg 4 is uniform flag
+    bool uniform = info[4]->BooleanValue();
+
+    // Arg 5 is accumulate flag
+    bool accumulate = info[5]->BooleanValue();
+/*
+    float rranges[] = { 0, 256 };
+    float granges[] = { 0, 256 };
+    float branges[] = { 0, 256 };
+
+    const float* histRange[] = { rranges, granges, branges};
+*/
     // Make a mat to hold the result image
     cv::Mat outputHist;
 
     // Perform calcHist
-    cv::calcHist(&inputImage, 1, 0, cv::Mat(), outputHist, 1, &histSize, &histRange, uniform, accumulate);
+    cv::calcHist(&inputImage, 1, channels, cv::Mat(), outputHist, dims, histSize, histRanges1, uniform, accumulate);
 
     // Wrap the output image
-    //Local<Object> outMatrixWrap = Nan::NewInstance(Nan::GetFunction(Nan::New(Matrix::constructor)).ToLocalChecked()).ToLocalChecked();
+    /*Local<Object> outMatrixWrap = Nan::NewInstance(Nan::GetFunction(Nan::New(Matrix::constructor)).ToLocalChecked()).ToLocalChecked();
-    //Matrix *outMatrix = Nan::ObjectWrap::Unwrap<Matrix>(outMatrixWrap);
+    Matrix *outMatrix = Nan::ObjectWrap::Unwrap<Matrix>(outMatrixWrap);
-    //outMatrix->mat = outputHist;
+    outMatrix->mat = outputHist;
 
-    v8::Local<v8::Array> arr = Nan::New<Array>(histSize);
+    info.GetReturnValue().Set(outMatrixWrap);*/
 
-    for (unsigned int i=0; i < (unsigned int) histSize; i++) {
+    v8::Local<v8::Array> arr = Nan::New<Array>(histSize[0]);
-      arr->Set(i, Nan::New<Number>(outputHist.at<float>(i)));
+
+    if(dims < 1 || dims > 3){
+      return Nan::ThrowTypeError("OPENCV nodejs binding error : only dimensions from 1 to 3 are allowed");
+    }
+
+    for (unsigned int i=0; i < (unsigned int) histSize[0]; i++) {
+      if(dims <= 1){
+        arr->Set(i, Nan::New<Number>(outputHist.at<float>(i)));
+      } else {
+        v8::Local<v8::Array> arr2 = Nan::New<Array>(dims);
+        for (unsigned int j=0; j < (unsigned int) histSize[1]; j++) {
+          if(dims <= 2){
+            arr2->Set(j, Nan::New<Number>(outputHist.at<float>(i,j)));
+          } else {
+            v8::Local<v8::Array> arr3 = Nan::New<Array>(dims);
+            for (unsigned int k=0; k < (unsigned int) histSize[1]; k++) {
+              arr3->Set(k, Nan::New<Number>(outputHist.at<float>(i,j,k)));
+            }
+            arr2->Set(j, arr3);
+          }
+        }
+        arr->Set(i, arr2);
+      }
     }
 
     info.GetReturnValue().Set(arr);