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WindowLevelFillLookupTable Method

Summary
Fills the user-allocated 8-bit LUT with values ranging between the startColor and endColor colors according to the selected LUT type.
Syntax
C#
VB
Objective-C
C++
public static void WindowLevelFillLookupTable( 
   RasterColor[] lookupTable, 
   RasterColor startColor, 
   RasterColor endColor, 
   int low, 
   int high, 
   int lowBit, 
   int highBit, 
   int minValue, 
   int maxValue, 
   int factor, 
   RasterPaletteWindowLevelFlags flags 
) 
Public Shared Sub WindowLevelFillLookupTable( _ 
   ByVal lookupTable() As RasterColor, _ 
   ByVal startColor As RasterColor, _ 
   ByVal endColor As RasterColor, _ 
   ByVal low As Integer, _ 
   ByVal high As Integer, _ 
   ByVal lowBit As Integer, _ 
   ByVal highBit As Integer, _ 
   ByVal minValue As Integer, _ 
   ByVal maxValue As Integer, _ 
   ByVal factor As Integer, _ 
   ByVal flags As RasterPaletteWindowLevelFlags _ 
)  
+(BOOL)windowLevelFillLookupTable:(NSArray*)lookupTable 
                       startColor:(LTRasterColor*)startColor 
                         endColor:(LTRasterColor*)endColor 
                              low:(int)low 
                             high:(int)high 
                           lowBit:(unsigned int)lowBit 
                          highBit:(unsigned int)highBit 
                         minValue:(int)minValue 
                         maxValue:(int)maxValue 
                           factor:(int)factor 
                            flags:(LTRasterPaletteWindowLevelFlags)flags 
                            error:(NSError**)outError; 
public: 
static void WindowLevelFillLookupTable(  
   array<RasterColor>^ lookupTable, 
   RasterColor startColor, 
   RasterColor endColor, 
   int low, 
   int high, 
   int lowBit, 
   int highBit, 
   int minValue, 
   int maxValue, 
   int factor, 
   RasterPaletteWindowLevelFlags flags 
)

Parameters

lookupTable
Pointer to an array to be updated with the 8-bit RGB quad (i.e. lookup table).

startColor
Starting color value for the gradient.

endColor
Ending color value for the gradient.

low
The low value of the window width, in pixels.

high
The high value for the window width, in pixels.

lowBit
Value indicating the low bit used for leveling.

This is normally 0 and should be less than the highBit.

highBit
Value indicating the high bit used for leveling.

This should be greater than or equal to lowBit and less than 11 for 12-bit grayscale or 15 for 16-bit grayscale.

minValue
The image minimum value. This value can be obtained using MinMaxValuesCommand.

maxValue
The image maximum value. This value can be obtained using MinMaxValuesCommand.

factor
Value that indicates the factor to be applied in the method operation specified in the flags parameter.

This parameter is used only if flags is RasterPaletteWindowLevelFlags.Exponential, RasterPaletteWindowLevelFlags.Logarithmic or RasterPaletteWindowLevelFlags.Sigmoid.

If RasterPaletteWindowLevelFlags.Exponential or RasterPaletteWindowLevelFlags.Sigmoid is specified, its value can be any integer (+/-). If RasterPaletteWindowLevelFlags.Logarithmic is specified, its value should be >>= 0. If factor = 0, the lookup table will be filled linearly.

flags
Flags that indicate how the range is used to fill and the type of the lookup table and whether it contains signed or unsigned data.

Remarks

This method is available in the Medical Toolkits.

Use this method to fill in the lookup table, used in RasterImage.WindowLevel, according to the lookup table type flag.

The lookup table will be filled as follows:

Inside/Outside MinValue-Low Low-High High-MaxValue
RasterPaletteWindowLevelFlags.Inside solid black (0,0,0) color gradient ranging from startColor to endColor solid white (255,255,255)
RasterPaletteWindowLevelFlags.Outside solid color (startColor) grayscale values from solid black (0,0,0) to solid white (255, 255, 255) solid color (endColor)
RasterPaletteWindowLevelFlags.Inside | RasterPaletteWindowLevelFlags.DicomStyle None color gradient ranging from startColor to endColor None
RasterPaletteWindowLevelFlags.Outside | RasterPaletteWindowLevelFlags.DicomStyle solid color (startColor) color gradient ranging from startColor to endColor solid color (endColor)

To fill a 16-bit lookup table use WindowLevelFillLookupTableExt.

Only TIFF and DICOM file formats are capable of saving images that have been window-leveled.

Images can be window-leveled by calling RasterImage.WindowLevel and specifying RasterWindowLevelMode.PaintAndProcessing for the flags parameter, by using the WindowLevelCommand or by loading an image from a file format that supports Window Leveling.

If a window-leveled image is saved as any other file format, the image data will be converted before being saved. For more information, refer to Saving Window-Leveled Images.

LEADTOOLS supports two types of LUTs for 10-16-bit grayscale images (8-bit LUT and 16-bit LUT). Typical grayscale image display and processing is done using an 8-bit LUT. But, you can also use a 16-bit LUT, which offers more precision. Some special video cards and monitors also support display of grayscale images using a 16-bit LUT.

For more information, refer to Introduction to Image Processing With LEADTOOLS.

For more information, refer to Grayscale Images.

Example
C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
 
 
public void WindowLevelFillLookupTableExample() 
{ 
	RasterCodecs codecs = new RasterCodecs(); 
 
	codecs.ThrowExceptionsOnInvalidImages = true; 
 
	string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); 
	string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_WindowLevel.tif"); 
 
	// Load an image as 8 bits/pixel 
	RasterImage image = codecs.Load(srcFileName, 8, CodecsLoadByteOrder.Rgb, 1, 1); 
 
	// change the image to be 16-bit grayscale 
	GrayscaleCommand grayscaleCmd = new GrayscaleCommand(16); 
	grayscaleCmd.Run(image); 
 
	// get the lookup table size 
	int lookupTableSize = 1 << (image.HighBit - image.LowBit + 1); 
 
	// get low/hight bits and minimum/maximum value of this grayscale image 
	MinMaxBitsCommand minMaxBitsCmd = new MinMaxBitsCommand(); 
	minMaxBitsCmd.Run(image); 
 
	int lowBit = minMaxBitsCmd.MinimumBit; 
	int highBit = minMaxBitsCmd.MaximumBit; 
 
	MinMaxValuesCommand minMaxValuesCmd = new MinMaxValuesCommand(); 
	minMaxValuesCmd.Run(image); 
	int minVal = minMaxValuesCmd.MinimumValue; 
	int maxVal = minMaxValuesCmd.MaximumValue; 
 
	// create the lookup table 
	RasterColor[] lookupTable = new RasterColor[lookupTableSize]; 
 
	RasterPaletteWindowLevelFlags flags = 
	   RasterPaletteWindowLevelFlags.Inside | 
	   RasterPaletteWindowLevelFlags.Linear; 
 
	if (image.Signed) 
		flags |= RasterPaletteWindowLevelFlags.Signed; 
 
	// initialize the fill lookup table parameters 
	RasterColor startColor = RasterColor.FromKnownColor(RasterKnownColor.Red); 
	RasterColor endColor = RasterColor.FromKnownColor(RasterKnownColor.Blue); 
 
	int low = 23000; 
	int high = 45000; 
	int factor = 10; 
 
	// fill the lookup table 
	RasterPalette.WindowLevelFillLookupTable( 
	   lookupTable, 
	   startColor, 
	   endColor, 
	   low, 
	   high, 
	   lowBit, 
	   highBit, 
	   minVal, 
	   maxVal, 
	   factor, 
	   flags); 
 
	// now do window level on the image 
	image.WindowLevel( 
	   lowBit, 
	   highBit, 
	   lookupTable, 
	   RasterWindowLevelMode.PaintAndProcessing); 
 
	// save it back on disk 
	codecs.Save(image, destFileName, RasterImageFormat.Tif, 16); 
 
	// Clean up 
	image.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS21\Resources\Images"; 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Core 
 
Public Sub WindowLevelFillLookupTableExample() 
   Dim codecs As RasterCodecs = New RasterCodecs() 
 
   codecs.ThrowExceptionsOnInvalidImages = True 
 
   Dim srcFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp") 
   Dim destFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1_WindowLevel.tif") 
 
   ' Load an image as 8 bits/pixel 
   Dim image As RasterImage = codecs.Load(srcFileName, 8, CodecsLoadByteOrder.Rgb, 1, 1) 
 
   ' change the image to be 16-bit grayscale 
   Dim grayscaleCmd As GrayscaleCommand = New GrayscaleCommand(16) 
   grayscaleCmd.Run(image) 
 
   ' get the lookup table size 
   Dim lookupTableSize As Integer = 1 << (image.HighBit - image.LowBit + 1) 
 
   ' get low/hight bits and minimum/maximum value of this grayscale image 
   Dim minMaxBitsCmd As MinMaxBitsCommand = New MinMaxBitsCommand() 
   minMaxBitsCmd.Run(image) 
 
   Dim lowBit As Integer = minMaxBitsCmd.MinimumBit 
   Dim highBit As Integer = minMaxBitsCmd.MaximumBit 
 
   Dim minMaxValuesCmd As MinMaxValuesCommand = New MinMaxValuesCommand() 
   minMaxValuesCmd.Run(image) 
   Dim minVal As Integer = minMaxValuesCmd.MinimumValue 
   Dim maxVal As Integer = minMaxValuesCmd.MaximumValue 
 
   ' create the lookup table 
   Dim lookupTable As RasterColor() = New RasterColor(lookupTableSize - 1) {} 
 
   Dim flags As RasterPaletteWindowLevelFlags = RasterPaletteWindowLevelFlags.Inside Or RasterPaletteWindowLevelFlags.Linear 
 
   If image.Signed Then 
      flags = flags Or RasterPaletteWindowLevelFlags.Signed 
   End If 
 
   ' initialize the fill lookup table parameters 
   Dim startColor As RasterColor = RasterColor.FromKnownColor(RasterKnownColor.Red) 
   Dim endColor As RasterColor = RasterColor.FromKnownColor(RasterKnownColor.Blue) 
 
   Dim low As Integer = 23000 
   Dim high As Integer = 45000 
   Dim factor As Integer = 10 
 
   ' fill the lookup table 
   RasterPalette.WindowLevelFillLookupTable(lookupTable, startColor, endColor, low, high, lowBit, highBit, minVal, maxVal, factor, flags) 
 
   ' now do window level on the image 
   image.WindowLevel(lowBit, highBit, lookupTable, RasterWindowLevelMode.PaintAndProcessing) 
 
   ' save it back on disk 
   codecs.Save(image, destFileName, RasterImageFormat.Tif, 16) 
 
   ' Clean up 
   image.Dispose() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\LEADTOOLS21\Resources\Images" 
End Class
Requirements

Target Platforms

Help Version 21.0.2021.7.2
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