Working with Grayscale Look-Up Tables

ImageGear provides an object and a set of methods for working with grayscale display LUTs. A grayscale LUT can be attached to an IGPage Object or to an IGPageDisplay Object. The LUT maps image pixel intensities to the contrast range of the display output. This can be used for displaying a specific range of image intensities, as well as for tone correction.

An IGLUT Object can have various input and output depths. Both input and output can be signed or unsigned.

The ImageGear Medical component provides a set of methods to build grayscale LUTs according to various DICOM display settings.

Example:

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Dim GrayLUT as IGLUT Dim Index as Long Dim Value as Long ` Create a LUT to converts 16-bit signed pixels to 8-bit unsigned Set GrayLUT = IGCoreCtl1.CreateObject(IG_OBJ_LUT) GrayLUT.ChangeAttrs(16, True, 8, False); ` Fill the LUT with a linear table, transforming 16-bit signed pixel range to 8-bit unsigned For Index = -32768 to 32767 Value = (index + 2048) / 256 GrayLUT.Item[Index] = Value Next Index ` Update image's grayscale LUT with the new data igPage.UpdateGrayscaleLUTFrom(GrayLUT);

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Dim GrayLUT as IGLUT
Dim Index as Long
Dim Value as Long
` Create a LUT to converts 16-bit signed pixels to 8-bit
unsigned
Set GrayLUT = IGCoreCtl1.CreateObject(IG_OBJ_LUT)
GrayLUT.ChangeAttrs(16, True, 8, False); 
` Fill the LUT with a linear table, transforming 16-bit signed
pixel range to 8-bit unsigned
For Index = -32768 to 32767
            Value = (index + 2048) / 256
            GrayLUT.Item[Index] = Value
Next Index
` Update image's grayscale LUT with the new data 
igPage.UpdateGrayscaleLUTFrom(GrayLUT);

Example:

See Also: