Emulation Tables

The LEAD Color Conversion toolkit provides emulation tables as one of its conversion methods. This method however is provided only for the following conversions:

CMYK to RGB.
CIELab to RGB.
RGB to CIELab.

The Emulation tables' method supports both built-in and custom options. For built-in emulation tables, use the ConversionMethodFlags.UseEmulationTables option. The custom emulation tables' option, ConversionMethodFlags.UseCustomEmulationTables, provides custom conversion using user-supplied images, converted from the source images distributed with the library, by any tool, as follows:

Conversion	Source	Convert to
CMYK to RGB	src_cmyk_image.tif	RGB image (i.e. dst_cmyk2rgb_image.tif)
RGB to Lab	src_rgb_image.tif	Lab image (i.e. dst_rgb2lab_image.tif)
Lab to RGB	src_lab_image.tif	RGB image (i.e. dst_lab2rgb_image.tif)

A set of images, already converted and ready for use (dst_cmyk2rgb_image.tif, dst_rgb2lab_image.tif, and dst_lab2rgb_image.tif), is provided. However, using the provided set of converted images will produce the same results as the built-in emulation tables.

The code below shows how a conversion can be done using the built-in tables:

Imports Leadtools  
Imports Leadtools.Codecs  
Imports Leadtools.ColorConversion 
              
Private Function BuiltInTablesConvertCmykToRgb(ByVal cmykBuffer As Byte(), ByVal width As Integer, ByVal height As Integer) As Byte() 
  ' StartUp the ColorConversion. 
  RasterColorConverter.Startup() 
                 
  ' Initialize the Rgb buffer array 
  Dim rgbBuffer As Byte() = New Byte(cmykBuffer.Length - 1){} 
                 
  ' Initialize a new ConversionParameters class object. 
  Dim convParams As ConversionParameters = New ConversionParameters() 
                 
  ' Conversion with options. 
  ' The conversion will be done with the options specified in the 
  ' convParams variable 
                 
  ' We want to use built-in emulation tables  
  convParams.Method = ConversionMethodFlags.UseEmulationTables 
              
  ' Set the quantization to 8 
  convParams.Quantization = 8 
                 
  ' set the active conversion method  
  convParams.ActiveMethod = ConversionMethodFlags.UseEmulationTables 
                 
  ' Initialize a new Converter object 
  Dim converter As RasterColorConverter = New RasterColorConverter() 
                 
  Try 
    ' Initialize the color conversion  
    converter.Start(ConversionColorFormat.Cmyk, ConversionColorFormat.Rgb, convParams) 
                 
    ' Convert the image buffer  
    converter.Convert(cmykBuffer, 0, rgbBuffer, 0, width, height, 0, 0) 
                 
    ' Stop the conversion  
    converter.Stop() 
  Catch ex As Exception 
    MessageBox.Show(ex.Message) 
    rgbBuffer = Nothing 
  End Try 
                 
  ' Shutdown the ColorConversion. 
  RasterColorConverter.Shutdown() 
                 
  ' return the converted buffer. 
  Return rgbBuffer 
End Function

using Leadtools;  
using Leadtools.Codecs;  
using Leadtools.ColorConversion; 
              
private byte[] BuiltInTablesConvertCmykToRgb(byte[] cmykBuffer, int width, int height) 
{ 
   // StartUp the ColorConversion. 
   RasterColorConverter.Startup(); 
              
   // Initialize the Rgb buffer array 
   byte[] rgbBuffer = new byte[cmykBuffer.Length]; 
              
   // Initialize a new ConversionParameters class object. 
   ConversionParameters convParams = new ConversionParameters(); 
              
   // Conversion with options. 
   // The conversion will be done with the options specified in the 
   // convParams variable 
              
   // We want to use built-in emulation tables  
   convParams.Method = ConversionMethodFlags.UseEmulationTables; 
              
   // set the active conversion method  
   convParams.ActiveMethod = ConversionMethodFlags.UseEmulationTables; 
              
   // set the quantization to 8 
   convParams.Quantization = 8; 
              
   // Initialize a new Converter object 
   RasterColorConverter converter = new RasterColorConverter(); 
              
   try 
   { 
      // Initialize the color conversion  
      converter.Start(ConversionColorFormat.Cmyk, 
          ConversionColorFormat.Rgb, 
          convParams); 
              
      // Convert the image buffer  
      converter.Convert(cmykBuffer, 0, rgbBuffer, 0, width, height, 0, 0); 
              
      // Stop the conversion  
      converter.Stop(); 
   } 
   catch (Exception ex) 
   { 
      MessageBox.Show(ex.Message); 
      rgbBuffer = null; 
   } 
              
   // Shutdown the ColorConversion. 
   RasterColorConverter.Shutdown(); 
              
   // return the converted buffer. 
   return rgbBuffer; 
}

The code below shows how a conversion can be done using user-defined tables:

Imports Leadtools  
Imports Leadtools.Codecs  
Imports Leadtools.ColorConversion 
              
Private Function UserTablesConvertCmykToRgb(ByVal cmykBuffer As Byte(), ByVal width As Integer, ByVal height As Integer) As Byte() 
   ' StartUp the ColorConversion. 
   RasterColorConverter.Startup() 
                  
   ' Initialize the Rgb buffer array 
   Dim rgbBuffer As Byte() = New Byte(cmykBuffer.Length - 1){} 
                  
   ' Initialize a new ConversionParameters class object. 
   Dim convParams As ConversionParameters = New ConversionParameters() 
                  
   ' Conversion with options. 
   ' The conversion will be done with the options specified in the  
   ' params(variable) 
                  
   ' we want to use custom emulation tables  
   convParams.Method = ConversionMethodFlags.UseCustomEmulationTables 
                  
   ' set the active conversion method  
   convParams.ActiveMethod = ConversionMethodFlags.UseCustomEmulationTables 
                  
   ' set the emulation tables  
   convParams.DestinationInputTable = "C:\LEADTOOLS21\Resources\Images\ET\src_rgb_image.tif" 
                  
   ' Initialize a new Converter object 
   Dim converter As RasterColorConverter = New RasterColorConverter() 
                  
   Try 
     ' Initialize the color conversion  
     converter.Start(ConversionColorFormat.Cmyk, ConversionColorFormat.Rgb, convParams) 
                  
     ' Convert the image buffer  
     converter.Convert(cmykBuffer, 0, rgbBuffer, 0, width, height, 0, 0) 
                  
     ' Stop the conversion  
     converter.Stop() 
   Catch ex As Exception 
     MessageBox.Show(ex.Message) 
     rgbBuffer = Nothing 
   End Try 
                  
   ' Shutdown the ColorConversion. 
   RasterColorConverter.Shutdown() 
                  
   ' return the converted buffer. 
   Return rgbBuffer 
End Function

using Leadtools;  
using Leadtools.Codecs;  
using Leadtools.ColorConversion; 
              
private byte[] UserTablesConvertCmykToRgb(byte[] cmykBuffer, int width, int height) 
{ 
   // StartUp the ColorConversion. 
   RasterColorConverter.Startup(); 
                
   // Initialize the Rgb buffer array 
   byte[] rgbBuffer = new byte[cmykBuffer.Length]; 
                
   // Initialize a new ConversionParameters class object. 
   ConversionParameters convParams = new ConversionParameters(); 
                
   // Conversion with options. 
   // The conversion will be done with the options specified in the  
   // params(variable) 
                
   // we want to use custom emulation tables  
   convParams.Method = ConversionMethodFlags.UseCustomEmulationTables; 
                
   // set the active conversion method  
   convParams.ActiveMethod = ConversionMethodFlags.UseCustomEmulationTables; 
                
   // set the emulation tables  
   convParams.DestinationInputTable = @"C:\LEADTOOLS21\Resources\Images\ET\src_rgb_image.tif"; 
                
   // Initialize a new Converter object 
   RasterColorConverter converter = new RasterColorConverter(); 
                
   try 
   { 
      // Initialize the color conversion  
      converter.Start(ConversionColorFormat.Cmyk, 
          ConversionColorFormat.Rgb, 
          convParams); 
                
      // Convert the image buffer  
      converter.Convert(cmykBuffer, 0, rgbBuffer, 0, width, height, 0, 0); 
                
      // Stop the conversion  
      converter.Stop(); 
   } 
   catch (Exception ex) 
   { 
      MessageBox.Show(ex.Message); 
      rgbBuffer = null; 
   } 
                
   // Shutdown the ColorConversion. 
   RasterColorConverter.Shutdown(); 
                
   // return the converted buffer. 
   return rgbBuffer; 
}