js-dicom/src/ImageUtility/getUncompressedImageFrame.js

this is js-dicom

import unpackBinaryFrame from './unpackBinaryFrame';

/**
 * Function to deal with extracting an image frame from an encapsulated data set.
 */

function getUncompressedImageFrame (dataSet, frameIndex) {
    const pixelDataElement = dataSet.elements.x7fe00010;
    const bitsAllocated = dataSet.uint16('x00280100');
    const rows = dataSet.uint16('x00280010');
    const columns = dataSet.uint16('x00280011');
    const samplesPerPixel = dataSet.uint16('x00280002');

    const pixelDataOffset = pixelDataElement.dataOffset;
    const pixelsPerFrame = rows * columns * samplesPerPixel;

    let frameOffset;

    if (bitsAllocated === 8) {
        frameOffset = pixelDataOffset + frameIndex * pixelsPerFrame;
        if (frameOffset >= dataSet.byteArray.length) {
            throw 'frame exceeds size of pixelData';
        }

        return new Uint8Array(dataSet.byteArray.buffer, frameOffset, pixelsPerFrame);
    } else if (bitsAllocated === 16) {
        frameOffset = pixelDataOffset + frameIndex * pixelsPerFrame * 2;
        if (frameOffset >= dataSet.byteArray.length) {
            throw 'frame exceeds size of pixelData';
        }

        return new Uint8Array(dataSet.byteArray.buffer, frameOffset, pixelsPerFrame * 2);
    } else if (bitsAllocated === 1) {
        frameOffset = pixelDataOffset + frameIndex * pixelsPerFrame * 0.125;
        if (frameOffset >= dataSet.byteArray.length) {
            throw 'frame exceeds size of pixelData';
        }

        return unpackBinaryFrame(dataSet.byteArray, frameOffset, pixelsPerFrame);
    }

    throw 'unsupported pixel format';
}

export default getUncompressedImageFrame;