LightControlCommand Class

Summary

Lightens or darkens all or part of an image by remapping the pixel values. This function is useful for pre-processing images for the purpose of improving barcode recognition results.

Syntax

Objective-C

C++

Java

public class LightControlCommand : RasterCommand

Public Class LightControlCommand  
   Inherits RasterCommand

@interface LTLightControlCommand : LTRasterCommand

public class LightControlCommand extends RasterCommand

public ref class LightControlCommand : public RasterCommand

Remarks

This class remaps the pixel values of the image across the full range of available pixel values, in order to achieve the values passed in LowerAverage, Average and UpperAverage. For example, call this method for a grayscale image, with Average containing 150, LowerAverage containing 100 and UpperAverage containing 190. The pixels of the image will be remapped so that the new average pixel value for the entire image will be 150, the new average value for those pixels with a value between 0 and the average value for the entire image will be 100, and the new average value for those pixels with a value between the average value for the entire image and the maximum pixel value in the image will be 190.
This class supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available only in the Document/Medical toolkits.
This class does not support signed data images.
For an example, see the following figure:
The following figure shows the same image, after the effect has been applied:
To obtain this effect, the following settings were used with the method: LowerAverage = 100 Average = 255 UpperAverage = 255 Type = LightControlCommandType.Yuv
This command does not support 32-bit grayscale images.

For more information, refer to Changing Brightness and Contrast. For more information, refer to Correcting Colors.

Example

Run the LightControlCommand on an image.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing.Color; 
 
public void LightControlCommandExample() 
{ 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "dirty_barcode.jpg")); 
 
   // Prepare the command 
   int[] LowerAverage = new int[3]; 
   int[] Average = new int[3]; 
   int[] UpperAverage = new int[3]; 
   LowerAverage[0] = 100;  //for blue, gray or yuv 
   LowerAverage[1] = 120;  //for green 
   LowerAverage[2] = 80;   //for red 
   Average[0] = 210;       //for blue, gray or yuv 
   Average[1] = 210;       //for green 
   Average[2] = 210;       //for red 
   UpperAverage[0] = 255;  //for blue, gray or yuv 
   UpperAverage[1] = 255;  //for green 
   UpperAverage[2] = 255;  //for red  
   LightControlCommand command = new LightControlCommand(LowerAverage, Average, UpperAverage, LightControlCommandType.Yuv); 
   // change the lightness of the image. 
   command.Run(image); 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Result.jpg"), RasterImageFormat.Jpeg, 24); 
 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS21\Resources\Images"; 
}

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing.Color 
 
Public Sub LightControlCommandExample() 
   Dim codecs As New RasterCodecs() 
   codecs.ThrowExceptionsOnInvalidImages = True 
 
   Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "dirty_barcode.jpg")) 
 
   ' Prepare the command 
   Dim LowerAverage() As Integer 
   ReDim LowerAverage(2) 
   Dim Average() As Integer 
   ReDim Average(2) 
   Dim UpperAverage() As Integer 
   ReDim UpperAverage(2) 
   LowerAverage(0) = 100  'for blue, gray or yuv 
   LowerAverage(1) = 120  'for green 
   LowerAverage(2) = 80   'for red 
   Average(0) = 210       'for blue, gray or yuv 
   Average(1) = 210       'for green 
   Average(2) = 210       'for red 
   UpperAverage(0) = 255  'for blue, gray or yuv 
   UpperAverage(1) = 255  'for green 
   UpperAverage(2) = 255  'for red  
   Dim command As LightControlCommand = New LightControlCommand(LowerAverage, Average, UpperAverage, LightControlCommandType.Yuv) 
   ' change the lightness of the image. 
   command.Run(leadImage) 
   codecs.Save(leadImage, Path.Combine(LEAD_VARS.ImagesDir, "Result.jpg"), RasterImageFormat.Jpeg, 24) 
 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\LEADTOOLS21\Resources\Images" 
End Class