HistogramGetRed Method (GdPictureImaging)

In This Topic

Computes the red channel histogram of a GdPicture image.

Syntax

Visual Basic
C#
Delphi
JScript
Managed Extensions for C++
C++/CLI

'Declaration
 
Public Function HistogramGetRed( _
   ByVal ImageID As Integer, _
   ByRef Data() As Integer _
) As GdPictureStatus

public GdPictureStatus HistogramGetRed( 
   int ImageID,
   ref int[] Data
)

public function HistogramGetRed( 
    ImageID: Integer;
   var  Data: Integerarray of
): GdPictureStatus;

public function HistogramGetRed( 
   ImageID : int,
   Data : int[]
) : GdPictureStatus;

public: GdPictureStatus HistogramGetRed( 
   int ImageID,
   ref int[]* Data
)

public:
GdPictureStatus HistogramGetRed( 
   int ImageID,
   array<int>^% Data
)

Parameters

ImageID: GdPicture image identifier.
Data: Output parameter. Array of 256 entries containing the red channel histogram data.

Return Value

A member of the GdPictureStatus enumeration.

Example

Getting the red channel histogram of a jpeg image and creating an image representing this histogram.

using (GdPictureImaging gdpictureImaging = new GdPictureImaging())
{
    int imageID = gdpictureImaging.CreateGdPictureImageFromFile("image.jpg", false);
 
    // Get the red channel histogram and the image dimensions.
    int[] histo = new int[256];
    gdpictureImaging.HistogramGetRed(imageID, ref histo);
    int count = gdpictureImaging.GetWidth(imageID) * gdpictureImaging.GetHeight(imageID);
 
    gdpictureImaging.ReleaseGdPictureImage(imageID);
 
    // Create an image representing the histogram. 
    // The image has the same width as the histogram and its height is 1000.                
    int histogramID = gdpictureImaging.CreateNewGdPictureImage(256, 1000, 24, Color.White);
    for (int i = 0; i < 256; i++)
    {
        int value = histo[i] * 1000 / count;
        for (int j = 0; j < value; j++)
        {
            gdpictureImaging.PixelSetColor(histogramID, i, j, Color.Red);
        }
    }
 
    gdpictureImaging.SaveAsPNG(histogramID, "histo.png");
    gdpictureImaging.ReleaseGdPictureImage(histogramID);
}

Reference

GdPictureImaging Class
GdPictureImaging Members