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:

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:

  VB

  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 

  C#

  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:

  VB

  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:\Users\Public\Documents\LEADTOOLS 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 

  C#

  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:\Users\Public\Documents\LEADTOOLS 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; 
  }