js-dicom/src/ImageUtility/internal/getModalityLUT.js

this is js-dicom

/**
 * This module generates a Modality LUT
 */



    function generateLinearModalityLUT(slope, intercept) {
        var localSlope = slope;
        var localIntercept = intercept;
        return function(sp) {
            return sp * localSlope + localIntercept;
        }
    }

    function generateNonLinearModalityLUT(modalityLUT) {
        var minValue = modalityLUT.lut[0];
        var maxValue = modalityLUT.lut[modalityLUT.lut.length -1];
        var maxValueMapped = modalityLUT.firstValueMapped + modalityLUT.lut.length;
        return function(sp) {
            if(sp < modalityLUT.firstValueMapped) {
                return minValue;
            }
            else if(sp >= maxValueMapped)
            {
                return maxValue;
            }
            else
            {
                return modalityLUT.lut[sp];
            }
        }
    }

    function getModalityLUT(slope, intercept, modalityLUT) {
        if (modalityLUT) {
            return generateNonLinearModalityLUT(modalityLUT);
        } else {
            return generateLinearModalityLUT(slope, intercept);
        }
    }

    // Module exports
    export  default getModalityLUT;