Leadtools.ImageProcessing.Color Send comments on this topic. | Back to Introduction - All Topics | Help Version 16.5.9.25
RemapHueCommand Class
See Also  Members   Example 



Uses a lookup table to change an image's hue values. The saturation and value tables change S and V values only if a particular hue value is marked as non-zero in the Mask property. It is used for all resolutions, including 48 and 64-bit images.

Syntax

Visual Basic (Declaration) 
Public Class RemapHueCommand 
   Inherits RasterCommand
   Implements IRasterCommand 
Visual Basic (Usage)Copy Code
Dim instance As RemapHueCommand
C# 
public class RemapHueCommand : RasterCommand, IRasterCommand 
C++/CLI 
public ref class RemapHueCommand : public RasterCommand, IRasterCommand 

Example

Run the RemapHueCommand on an image and change all green hues (and hues near green).

Visual BasicCopy Code
Public Function INCREMENT_S1(ByVal x As Integer, ByVal Length As Integer) As Integer
   Return ((x + 1) Mod Length)
End Function
Public Function DECREMENT_S1(ByVal x As Integer, ByVal Length As Integer) As Integer
   Return ((x + (Length - 1)) Mod Length)
End Function

Public Function ADD_S1(ByVal x As Integer, ByVal y As Integer, ByVal Length As Integer) As Integer
   Return ((x + y) Mod Length)
End Function


Public Sub RemapHueCommandCommandExample()
   RasterCodecs.Startup()
   Dim codecs As New RasterCodecs()
   codecs.ThrowExceptionsOnInvalidImages = True

   Dim leadImage As RasterImage = codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "Master.jpg")

   ' Prepare the command
   Dim MaskTable() As Integer
   Dim HueTable() As Integer
   Dim hsvRef As RasterHsvColor
   Dim HueGreen As Integer
   Dim HueChange As Integer

   Dim Change As Integer
   Dim i As Integer
   Dim Count As Integer
   Dim Length As Integer

   If (leadImage.BitsPerPixel >= 48) Then

      Length = 65536

   ElseIf (Not (leadImage.BitsPerPixel = 16 Or leadImage.BitsPerPixel = 12)) Then
      Length = 256
   ElseIf (IsNothing(leadImage.GetLookupTable) And leadImage.UseLookupTable) Then
      Length = 256
   Else
      Length = (1 << leadImage.BitsPerPixel)
   End If
   'Allocate tables
   ReDim MaskTable(Length - 1)
   ReDim HueTable(Length - 1)

   'Initialize tables
   For i = 0 To Length - 1
      MaskTable(i) = 0
      HueTable(i) = i
   Next

   'Get the hue for green
   hsvRef = RasterHsvColor.FromRasterColor(New RasterColor(0, 255, 0))

   HueGreen = hsvRef.H

   'Obtain new hue
   hsvRef = RasterHsvColor.FromRasterColor(New RasterColor(255, 128, 0))
   Change = hsvRef.H - HueGreen
   If (Change > 0) Then
      HueChange = Change
   Else
      HueChange = Change + Length - 1
   End If

   HueGreen = (HueGreen * (Length - 1)) \ 255
   HueChange = (HueChange * (Length - 1)) \ 255

   'Set values in HueTable, MaskTable
   HueTable(HueGreen) = HueTable(HueGreen) + HueChange
   MaskTable(HueGreen) = 1

   'set the hues near green (+/- 15)
   i = INCREMENT_S1(HueGreen, Length)

   For Count = (15 * (Length - 1)) \ 255 To 1 Step -1
      i = INCREMENT_S1(i, Length)
      HueTable(i) = ADD_S1(HueTable(i), HueChange, Length)
      MaskTable(i) = 1
   Next

   i = DECREMENT_S1(HueGreen, Length)

   For Count = (15 * (Length - 1)) \ 255 To 1 Step -1

      i = DECREMENT_S1(i, Length)
      HueTable(i) = ADD_S1(HueTable(i), HueChange, Length)
      MaskTable(i) = 1
   Next
   Dim command As RemapHueCommand = New RemapHueCommand(MaskTable, HueTable, Nothing, Nothing, Length)

   command.Run(leadImage)
   codecs.Save(leadImage, LeadtoolsExamples.Common.ImagesPath.Path + "Result.jpg", RasterImageFormat.Jpeg, 24)

   RasterCodecs.Shutdown()
End Sub
C#Copy Code
public int INCREMENT_S1(int x, int Length) 
{ 
   return ((x + 1) % Length); 
} 
public int DECREMENT_S1(int x, int Length) 
{ 
   return ((x + (Length - 1)) % Length); 
} 
 
public int ADD_S1(int x, int y, int Length) 
{ 
   return ((x + y) % Length); 
} 
 
 
public void RemapHueCommandCommandExample() 
{ 
   // Load an image 
   RasterCodecs.Startup(); 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
 
   RasterImage image = codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "Master.jpg"); 
 
   // Prepare the command 
   int[]  MaskTable; 
   int[]  HueTable; 
   RasterHsvColor hsvRef; 
   int    HueGreen, HueChange; 
   int    Change; 
   int    i, Count; 
   int    Length; 
 
   if(image.BitsPerPixel >= 48) 
      Length = 0x10000; 
   else if(!(image.BitsPerPixel == 16 || image.BitsPerPixel == 12)) 
      Length = 256; 
   else if(image.GetLookupTable() != null && image.UseLookupTable) 
      Length = 256; 
   else 
      Length = (1 << image.BitsPerPixel); 
 
   //Allocate tables 
   MaskTable = new int[Length]; 
   HueTable  = new int[Length]; 
 
   //Initialize tables 
   for (i = 0; i < Length; i++) 
   { 
      MaskTable[i] = 0; 
      HueTable[i] = i; 
   } 
 
   //Get the hue for green 
   hsvRef = RasterHsvColor.FromRasterColor(new RasterColor(0,255,0)); 
 
   HueGreen = hsvRef.H; 
 
   //Obtain new hue   
   hsvRef =  RasterHsvColor.FromRasterColor(new RasterColor(255, 128, 0)); 
   Change = (int)hsvRef.H - (int)HueGreen; 
   HueChange = (Change>0) ? (int)Change : (int)(Change + Length - 1); 
   HueGreen   *= (Length - 1)/255; 
   HueChange *= (Length - 1)/255; 
 
   //Set values in HueTable, MaskTable  
   HueTable[HueGreen] = (HueTable[HueGreen] + HueChange); 
   MaskTable[HueGreen] = 1; 
 
   //set the hues near green (+/- 15) 
   Count = (15 * (Length - 1))/255; 
   for (i = INCREMENT_S1(HueGreen, Length); Count > 0; i = INCREMENT_S1(i, Length), Count--) 
   { 
      HueTable[i] = ADD_S1(HueTable[i], HueChange, Length); 
      MaskTable[i] = 1; 
   } 
 
   Count = (15 * (Length - 1))/255; 
   for (i = DECREMENT_S1(HueGreen, Length); Count > 0; i = DECREMENT_S1(i, Length), Count--) 
   { 
      HueTable[i] = ADD_S1(HueTable[i], HueChange, Length); 
      MaskTable[i] = 1; 
   } 
 
   RemapHueCommand command = new RemapHueCommand(MaskTable, HueTable, null, null, Length); 
   command.Run(image); 
   codecs.Save(image, LeadtoolsExamples.Common.ImagesPath.Path + "Result.jpg", RasterImageFormat.Jpeg, 24); 
 
   RasterCodecs.Shutdown(); 
}

Remarks

  • This command can be used to change a range of colors to another range of colors. For example, it could be used to change all red pixels to any color, where a red pixel can have any brightness (V) and any amount of white (saturation). A red pixel in this case would be RGB(x,y,y) where 0 <= x <(LookUpTableLength - 1) and 0 <= y < x or in the HSV color space HSV(0,x,x) where 0<=x<=(LookUpTableLength - 1)
  • The Mask lookup table identifies which values in the HueTable are valid. If a Mask value is 0, then the corresponding value in the HueTable is ignored. If a Mask value is non-zero, then the corresponding value in the HueTable is used. For example, if a pixel has a hue value of 240 and Mask[240] is nonzero, then the hue value of 240 is replaced with HueTable[240]. Traditionally, hue ranges from 0 to 359. For the lookup table, the range of 0 to 359 is remapped to a range of 0.. LookUpTableLength - 1. For example, if LookUpTableLength = 256
  • This command supports 48 and 64-bit colored images.
  • This command does not support signed data images.
  • This command does not support 32-bit grayscale images.
For more information, refer to Changing Brightness and Contrast.

Inheritance Hierarchy

System.Object
   Leadtools.ImageProcessing.RasterCommand
      Leadtools.ImageProcessing.Color.RemapHueCommand

Requirements

Target Platforms: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also