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GetPixelData(int,int) Method

Summary

Returns the pixel data of the specified pixel.

Syntax
C#
VB
Java
Objective-C
C++
public byte[] GetPixelData( 
   int row, 
   int column 
) 
Public Overloads Function GetPixelData( _ 
   ByVal row As Integer, _ 
   ByVal column As Integer _ 
) As Byte() 
- (BOOL)getData:(void *)data  
         ofSize:(unsigned long)size  
  forPixelAtRow:(NSInteger)row  
         column:(NSInteger)column  
          error:(NSError **)error 
public byte[] getPixelData( 
  int row,  
  int column 
) 
public: 
array<byte>^ GetPixelData(  
   int row, 
   int column 
)  

Parameters

row
The zero-based row number of the pixel.

column
The zero-based column number of the pixel

Return Value

This method returns a byte array which may represent an index into an images's palette, a grayscale value (Document/Medical only), or red, green, and blue color values.

Remarks

The image memory must be locked when you use this method. Normally, you can call Access to lock the memory before starting an operation that uses this method. Then call Release when the operation is finished.

No transformations are performed on the pixel data.

This method should be called only for 8, 16, 24, 32, 48 and 64-bit images. It works as follows:

  • For 8-bit images, this method will retrieve the palette index for the specified pixel.
  • For 16-bit images, this method will retrieve the 2-byte value that forms the pixel.
  • For 24-bit images, this method will retrieve the 3 bytes containing the pixel color. The Order determines whether the data is RGB or BGR.
  • For 32-bit images, this method will retrieve the 4 bytes containing the pixel color and alpha information. The first 3 bytes contain the pixel color. The Order determines whether the data in the first 3 bytes is RGB or BGR. The 4th byte is the alpha channel information.
  • For 48-bit images, this method will retrieve the 6 bytes containing the pixel color. The Order determines whether the data is RGB or BGR. Each color component is stored as a 16-bit value, where 0 corresponds to black and 0xFFFF corresponds to full white.
  • For 64-bit images, this method will retrieve the 8 bytes containing the pixel color and alpha information. The Order determines whether the data in the first 6 bytes is RGB or BGR. Each color component is stored as a 16-bit value, where 0 corresponds to black and 0xFFFF corresponds to full white. The last two bytes contain the alpha information (also stored as a short value).

The minimum size of the returned byte array is calculated:

(BitsPerPixel + 7) / 8

You can use the SetPixelData method to assign the returned value to another pixel.

This method uses image coordinates to specify the pixel. Therefore, you must account for the view perspective of the image. If you specify a pixel that is outside the image or outside the region (if the image has one), this method throws an exception.

The SetPixelData method changes the data of the specified pixel.

For more information, refer to Introduction to Image Processing With LEADTOOLS.

For more information refer to Accounting for View Perspective.

Example

This example uses the GetPixelData and SetPixelData methods to swap the R and G values for a particular pixel.

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Dicom; 
using Leadtools.Drawing; 
using Leadtools.Controls; 
using LeadtoolsExamples.Common; 
using Leadtools.Svg; 
 
public void GetPixelDataExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
   // Load the image 
   RasterImage image = codecs.Load(Path.Combine(ImagesPath.Path, "IMAGE1.CMP")); 
 
   if (image.BitsPerPixel == 24) 
   { 
      byte[] Data; 
      byte Value; 
      int Row = 10, Column = 20; 
 
      image.Access(); 
 
      Data = image.GetPixelData(Row, Column); 
      // swap the R and B values 
      Value = Data[0]; Data[0] = Data[2]; Data[2] = Value; 
 
      // put back the transformed pixel 
      image.SetPixelData(Row, Column, Data); 
 
      image.Release(); 
   } 
 
   codecs.Save(image, Path.Combine(ImagesPath.Path, "IMAGE1_GetPixelData.BMP"), RasterImageFormat.Bmp, 0); 
 
   image.Dispose(); 
   codecs.Dispose(); 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Core 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Controls 
Imports Leadtools.Dicom 
Imports Leadtools.Drawing 
Imports Leadtools.Svg 
 
Public Sub GetPixelDataExample() 
   Dim codecs As RasterCodecs = New RasterCodecs() 
   ' Load the image 
   Dim image As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1.CMP")) 
 
   If image.BitsPerPixel = 24 Then 
      Dim Data As Byte() 
      Dim Value As Byte 
      Dim Row As Integer = 10, Column As Integer = 20 
 
      image.Access() 
 
      Data = image.GetPixelData(Row, Column) 
      ' swap the R and B values 
      Value = Data(0) 
      Data(0) = Data(2) 
      Data(2) = Value 
 
      ' put back the transformed pixel 
      image.SetPixelData(Row, Column, Data) 
 
      image.Release() 
   End If 
 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1_GetPixelData.BMP"), RasterImageFormat.Bmp, 0) 
 
   image.Dispose() 
   codecs.Dispose() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class 
c#[Silverlight C# Example] 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Dicom; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Examples; 
using Leadtools.Windows.Media; 
 
public void GetPixelDataExample(RasterImage image, Stream destStream) 
{ 
   if (image.BitsPerPixel == 24) 
   { 
      byte[] Data; 
      byte Value; 
      int Row = 10, Column = 20; 
 
      image.Access(); 
 
      Data = image.GetPixelData(Row, Column); 
      // swap the R and B values 
      Value = Data[0]; Data[0] = Data[2]; Data[2] = Value; 
 
      // put back the transformed pixel 
      image.SetPixelData(Row, Column, Data); 
 
      image.Release(); 
   } 
 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.Save(image, destStream, RasterImageFormat.Bmp, 0); 
 
   image.Dispose(); 
} 
vb[Silverlight VB Example] 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Dicom 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Core 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Windows.Media 
 
Public Sub GetPixelDataExample(ByVal image As RasterImage, ByVal destStream As Stream) 
   If image.BitsPerPixel = 24 Then 
      Dim Data As Byte() 
      Dim Value As Byte 
      Dim Row As Integer = 10, Column As Integer = 20 
 
      image.Access() 
 
      Data = image.GetPixelData(Row, Column) 
      ' swap the R and B values 
      Value = Data(0) 
      Data(0) = Data(2) 
      Data(2) = Value 
 
      ' put back the transformed pixel 
      image.SetPixelData(Row, Column, Data) 
 
      image.Release() 
   End If 
 
   Dim codecs As RasterCodecs = New RasterCodecs() 
   codecs.Save(image, destStream, RasterImageFormat.Bmp, 0) 
 
   image.Dispose() 
End Sub 

Requirements

Target Platforms

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