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CountLookupTableColorsExt Method

Gets the total number of entries between the start color and the end color, and the index of the last occurrence of the start color. The start and end colors are determined internally.
Public Shared Function CountLookupTableColorsExt( _ 
   ByVal lookupTable() As RasterColor16, _ 
   ByVal type As CountLookupTableColorsType _ 
) As CountLookupTableColorsResult 
+ (nullable LTCountLookupTableColorsResult *)countLookupTableColorsExt:(nullable NSArray<LTRasterColor16 *> *)lookupTable 
                                                                error:(NSError **)error 
public static CountLookupTableColorsResult countLookupTableColorsExt( 
   RasterColor16[] lookupTable,  
   CountLookupTableColorsType type 


16-bit-bit lookup table array to be filled by this method.

Flag that indicates whether the LookupTable contains signed or unsigned data.

  • Suppose you have a LookupTable with 4096 colors, the first 200 colors are black and the last 30 are white, the rest of the colors between black and white are gray. This is what the method will provide : NumberOfEntries (property of CountLookupTableColorsResult) : 3868. FirstIndex (property of CountLookupTableColorsResult) : 199.

  • In more detail this is: Total number of entries: 4096 (0 - 4095). First index of the end color: 4095 - 30 + 1 (+1 to add the first index of the end color to the range). Number of occurrences of the starting color: 200 (0 - 199). The last index of the start color: 199. Total number of entries: (4095 - 30 + 1) - 199 + 1.

  • This method supports 12 and 16-bit grayscale images. Support for 12 and 16-bit grayscale images is available only in the Document/Medical toolkits.

  • This method uses 16-bit lookup tables. See CountLookupTableColors for a method that uses 8-bit lookup tables.

Run the CountLookupTableColorsExt method to get the number of entries and start index from the image.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
using LeadtoolsExamples.Common; 
public void CountLookupTableColorsExtExample() 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
   codecs.ThrowExceptionsOnInvalidImages = true; 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Image2.dcm")); 
   // Prepare the command 
   CountLookupTableColorsResult command = CoreUtilities.CountLookupTableColorsExt(image.GetLookupTable16(), CountLookupTableColorsType.Signed); 
   MessageBox.Show("First Index = " + command.FirstIndex + "\n" + 
      "Number Of Entries = " + command.NumberOfEntries); 
static class LEAD_VARS 
   public const string ImagesDir = @"C:\LEADTOOLS21\Resources\Images"; 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing.Core 
Public Sub CountLookupTableColorsExtExample() 
   Dim codecs As New RasterCodecs() 
   codecs.ThrowExceptionsOnInvalidImages = True 
   Dim leadImage As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE2.dcm")) 
   ' Prepare the command 
   Dim command As CountLookupTableColorsResult = CoreUtilities.CountLookupTableColorsExt(leadImage.GetLookupTable16, CountLookupTableColorsType.Signed) 
   MessageBox.Show("First Index = " + command.FirstIndex.ToString + Chr(13) + "Number Of Entries = " + command.NumberOfEntries.ToString) 
End Sub 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\LEADTOOLS21\Resources\Images" 
End Class 

Target Platforms

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Leadtools.ImageProcessing.Core Assembly