js-dicom/src/ImageUtility/colorSpaceConverters/convertRGBColorByPlane.js

this is js-dicom

export default function (imageFrame, rgbaBuffer) {
    if (imageFrame === undefined) {
        throw new Error('decodeRGB: rgbBuffer must not be undefined');
    }
    if (imageFrame.length % 3 !== 0) {
        throw new Error('decodeRGB: rgbBuffer length must be divisible by 3');
    }

    const numPixels = imageFrame.length / 3;
    let rgbaIndex = 0;
    let rIndex = 0;
    let gIndex = numPixels;
    let bIndex = numPixels * 2;

    for (let i = 0; i < numPixels; i++) {
        rgbaBuffer[rgbaIndex++] = imageFrame[rIndex++]; // red
        rgbaBuffer[rgbaIndex++] = imageFrame[gIndex++]; // green
        rgbaBuffer[rgbaIndex++] = imageFrame[bIndex++]; // blue
        rgbaBuffer[rgbaIndex++] = 255; // alpha
    }
}