TImageEnProc.CalcDensityHistogram

Declaration

procedure CalcDensityHistogram(VertHist, HorzHist: Pointer; VertMax, HorzMax: Integer);

Description

Calculate the vertical and horizontal density histograms. VertHist and HorzHist are an array of Integer that will be filled with density values (between 0 and max values).

Note: If the image PixelFormat is not ie1g, ie24RGB or ie32RGB, it will be converted

Demos

Examples

Also see: Automated Samples

var
  vertHist, horzHist: PIntegerArray;
  vertHistHeight, horzHistWidth, vertHistWidth, horzHistHeight: Integer;
  i: Integer;
begin
  ImageEnView1.IO.LoadFromFile( ImageEnView1.IO.ExecuteOpenDialog() );

  // Histograms
  vertHistWidth  := ienVertHist.ClientWidth;
  vertHistHeight := ImageEnView1.IEBitmap.Height;
  horzHistWidth  := ImageEnView1.IEBitmap.Width;
  horzHistHeight := ienHorzHist.ClientHeight;

  GetMem( vertHist, IECheckedBufferSize( vertHistHeight, SizeOf(Integer) ));  // v15.2.1
  GetMem( horzHist, IECheckedBufferSize( horzHistWidth, SizeOf(Integer) ));   // v15.2.1
  try
    ImageEnView1.Proc.CalcDensityHistogram( vertHist, horzHist, vertHistWidth, horzHistHeight );

    // Draw horizontal histogram
    ienHorzHist.IEBitmap.Allocate( horzHistWidth, horzHistHeight, ienHorzHist.Background );
    ienHorzHist.IEBitmap.Canvas.Pen.Color := clBlack;
    for i := 0 to horzHistWidth - 1 do
    begin
      ienHorzHist.IEBitmap.Canvas.MoveTo( i, horzHistHeight );
      ienHorzHist.IEBitmap.Canvas.LineTo( i, horzHistHeight - horzHist[i] );
    end;
    ienHorzHist.Update();

    // Draw vertical histogram
    ienVertHist.IEBitmap.Allocate( vertHistWidth, vertHistHeight, ienVertHist.Background );
    ienVertHist.IEBitmap.Canvas.Pen.Color := clBlack;
    for i := 0 to vertHistHeight - 1 do
    begin
      ienVertHist.IEBitmap.Canvas.MoveTo( 0, i );
      ienVertHist.IEBitmap.Canvas.LineTo( vertHist[i], i );
    end;
    ienVertHist.Update();
  finally
    FreeMem( vertHist );
    FreeMem( horzHist );
  end;
end;


// Load test image
ImageEnView1.IO.LoadFromFile( 'D:\TestImage.jpg' );

  

// Draw density histograms for the image
GetMem(vertoHist, ImageEnView2.IEBitmap.Height * SizeOf(Integer));
GetMem(horzoHist, ImageEnView2.IEBitmap.Width * SizeOf(Integer));
ImageEnView1.Proc.CalcDensityHistogram( vertHisto, horzHisto, ImageEnView2.IEBitmap.Width, ImageEnView2.IEBitmap.Height );
ImageEnView2.IEBitmap.Canvas.Pen.Color := clNavy;
for i := 0 to ImageEnView2.IEBitmap.Width - 1 do
begin
  ImageEnView2.IEBitmap.Canvas.MoveTo( i, ImageEnView2.IEBitmap.Height );
  ImageEnView2.IEBitmap.Canvas.LineTo( i, ImageEnView2.IEBitmap.Height - horzHisto[i] );
end;
ImageEnView2.Update();
FreeMem( vertHist );
FreeMem( horzHist );

  

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