Grayscale Look-Up Tables

Grayscale Look Up Tables map a 8…16 bit image to 8 bit grayscale, allowing you to display a specific contrast range of an image, or to apply a non-linear transform to the image pixels for display. Many image processing functions also take the grayscale Look Up Tables into account, and apply processing on the contrast range specified by the grayscale LUT rather on the whole contrast range.

ImageGear provides a set of functions for working with grayscale LUTs. A grayscale LUT object is represented as an opaque handle: HIGLUT. Use the IG_LUT_... group of functions to create, destroy, and access features of grayscale LUTs.

ImageGear allows you to attach grayscale LUTs to images and to image display settings.

An HIGLUT 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 API functions that allows you to build grayscale LUTs according to various DICOM display settings.

Example:

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HIGLUT GrayLUT; AT_INT index; // Create a LUT IG_LUT_create(12, TRUE, 8, FALSE, &GrayLUT); // Fill the LUT with a linear table, transforming 12-bit signed image to 8-bit unsigned for (index = -2048; index<2048; index++) { value = (index + 2048) / 16; IG_LUT_item_set(GrayLUT, index, value); } IG_image_grayscale_LUT_update_from(hIGear, GrayLUT);

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HIGLUT GrayLUT;
AT_INT index;
// Create a LUT
IG_LUT_create(12, TRUE, 8, FALSE, &GrayLUT);
// Fill the LUT with a linear table, transforming 12-bit signed image to 8-bit
unsigned
for (index = -2048; index<2048; index++)
{
        value = (index + 2048) / 16;
        IG_LUT_item_set(GrayLUT, index, value);
}
IG_image_grayscale_LUT_update_from(hIGear, GrayLUT);

Example:

See Also: