<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:10pt"><div id="yiv0584275477"><div><div style="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 10pt;"><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9">Hi,</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br></div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9">I have a grayscale image. I want to draw a histogram where x-axis is the nth column (n = image_width -1), and y-axis is the sum of pixel value in each column. How do I pass the y-axis value (std::vector<int> ColSum; ) to the vtkImageAccumulate?</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br></div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9">// Read a jpeg image</div><div
id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> vtkSmartPointer<vtkJPEGReader> reader =</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> vtkSmartPointer<vtkJPEGReader>::New();</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9">
reader->SetFileName( argv[1] );</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> reader->Update();</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br></div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9">// Convert image to image data</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> vtkSmartPointer<vtkImageData> imageData =</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><span class="yiv0584275477Apple-tab-span" style="white-space:pre;"> </span>vtkSmartPointer<vtkImageData>::New();</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> imageData = reader->GetOutput();</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br></div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9">// Compute the sum for each image column </div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> std::vector<int>
ColSum; </div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> int image_width = imageData->GetDimensions()[0];</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> ColSum.resize(width);</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> </div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> for(int i = 0; i < image_width; ++i)</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> {</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><span class="yiv0584275477Apple-tab-span" style="white-space:pre;"> </span> ColSum[i] = 0;</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><span class="yiv0584275477Apple-tab-span" style="white-space:pre;"> </span> for(int j = 0; j < height; ++j)</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><span class="yiv0584275477Apple-tab-span" style="white-space:pre;"> </span> {</div><div
id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><span class="yiv0584275477Apple-tab-span" style="white-space:pre;"> </span> ColSum[i] += imageData->GetScalarComponentAsDouble(i,j, 0, 0);</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><span class="yiv0584275477Apple-tab-span" style="white-space:pre;"> </span>
}</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> }</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_15"></div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9" style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">// Draw histogram</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> vtkSmartPointer<vtkImageAccumulate> histogram =</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> vtkSmartPointer<vtkImageAccumulate>::New();</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> // ??? How to convert <span style="font-size: 10pt;"> "</span><span style="font-size: 10pt;">ColSum" to vtkImageAccumulate here?</span></div><div
id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br></div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"> ...</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br></div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br></div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9">Regards,</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9">Harold</div><div id="yiv0584275477yui_3_13_0_ym1_7_1389094084864_9"><br></div></div></div></div></div></body></html>