GetPixelData(int,int) Method

Summary

Returns the pixel data of the specified pixel.

Syntax

Objective-C

C++/CLI

Java

Python

public byte[] GetPixelData( 
   int row, 
   int column 
)

- (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 
)

def GetPixelData(self,row,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.

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 Leadtools.Svg; 
 
 
public void GetPixelDataExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
   // Load the image 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "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(LEAD_VARS.ImagesDir, "IMAGE1_GetPixelData.BMP"), RasterImageFormat.Bmp, 0); 
 
   image.Dispose(); 
   codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS23\Resources\Images"; 
}

Requirements

Target Platforms

Reference

RasterImage Class

RasterImage Members

Overload List

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Help Version 23.0.2024.5.22

Leadtools Assembly

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Getting Started

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Leadtools Namespace

Leadtools.ImageProcessing Namespace

Assemblies