@cleerlycode/cornerstone-wado-image-loader
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Cornerstone ImageLoader for DICOM WADO-URI
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<h2><a href="index.html">Home</a></h2><h3>Global</h3><ul><li><a href="global.html#addTask">addTask</a></li><li><a href="global.html#arrayBufferToString">arrayBufferToString</a></li><li><a href="global.html#cacheSizeInBytes">cacheSizeInBytes</a></li><li><a href="global.html#cancelTask">cancelTask</a></li><li><a href="global.html#framesAreFragmented">framesAreFragmented</a></li><li><a href="global.html#getNumberString">getNumberString</a></li><li><a href="global.html#getNumberValues">getNumberValues</a></li><li><a href="global.html#getStatistics">getStatistics</a></li><li><a href="global.html#getTransferSyntaxForContentType">getTransferSyntaxForContentType</a></li><li><a href="global.html#getUncompressedImageFrame">getUncompressedImageFrame</a></li><li><a href="global.html#getValue">getValue</a></li><li><a href="global.html#handleMessageFromWorker">handleMessageFromWorker</a></li><li><a href="global.html#handler">handler</a></li><li><a href="global.html#initialize">initialize</a></li><li><a href="global.html#loadCodecs">loadCodecs</a></li><li><a href="global.html#loadWebWorkerTask">loadWebWorkerTask</a></li><li><a href="global.html#registerLoaders">registerLoaders</a></li><li><a href="global.html#registerTaskHandler">registerTaskHandler</a></li><li><a href="global.html#setPixelDataType">setPixelDataType</a></li><li><a href="global.html#setTaskPriority">setTaskPriority</a></li><li><a href="global.html#spawnWebWorker">spawnWebWorker</a></li><li><a href="global.html#startTaskOnWebWorker">startTaskOnWebWorker</a></li><li><a href="global.html#unpackBinaryFrame">unpackBinaryFrame</a></li></ul>
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<h1 class="page-title">imageLoader/createImage.js</h1>
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<pre class="prettyprint source linenums"><code>import { external } from '../externalModules.js';
import getImageFrame from './getImageFrame.js';
import decodeImageFrame from './decodeImageFrame.js';
import isColorImageFn from './isColorImage.js';
import convertColorSpace from './convertColorSpace.js';
import getMinMax from '../shared/getMinMax.js';
import isJPEGBaseline8BitColor from './isJPEGBaseline8BitColor.js';
let lastImageIdDrawn = '';
function isModalityLUTForDisplay(sopClassUid) {
// special case for XA and XRF
// https://groups.google.com/forum/#!searchin/comp.protocols.dicom/Modality$20LUT$20XA/comp.protocols.dicom/UBxhOZ2anJ0/D0R_QP8V2wIJ
return (
sopClassUid !== '1.2.840.10008.5.1.4.1.1.12.1' && // XA
sopClassUid !== '1.2.840.10008.5.1.4.1.1.12.2.1'
); // XRF
}
function convertToIntPixelData(floatPixelData) {
const floatMinMax = getMinMax(floatPixelData);
const floatRange = Math.abs(floatMinMax.max - floatMinMax.min);
const intRange = 65535;
const slope = floatRange / intRange;
const intercept = floatMinMax.min;
const numPixels = floatPixelData.length;
const intPixelData = new Uint16Array(numPixels);
let min = 65535;
let max = 0;
for (let i = 0; i < numPixels; i++) {
const rescaledPixel = Math.floor((floatPixelData[i] - intercept) / slope);
intPixelData[i] = rescaledPixel;
min = Math.min(min, rescaledPixel);
max = Math.max(max, rescaledPixel);
}
return {
min,
max,
intPixelData,
slope,
intercept
};
}
/**
* Helper function to set pixel data to the right typed array. This is needed because web workers
* can transfer array buffers but not typed arrays
* @param imageFrame
*/
function setPixelDataType(imageFrame) {
if (imageFrame.bitsAllocated === 32) {
imageFrame.pixelData = new Float32Array(imageFrame.pixelData);
} else if (imageFrame.bitsAllocated === 16) {
if (imageFrame.pixelRepresentation === 0) {
imageFrame.pixelData = new Uint16Array(imageFrame.pixelData);
} else {
imageFrame.pixelData = new Int16Array(imageFrame.pixelData);
}
} else {
imageFrame.pixelData = new Uint8Array(imageFrame.pixelData);
}
}
function createImage (imageId, pixelData, transferSyntax, options) {
if (!pixelData || !pixelData.length) {
return Promise.reject(new Error('The file does not contain image data.'));
}
const cornerstone = external.cornerstone;
const canvas = document.createElement('canvas');
const imageFrame = getImageFrame(imageId);
const decodePromise = decodeImageFrame(
imageFrame,
transferSyntax,
pixelData,
canvas,
options
);
const getMetaData = key => cornerstone.metaData.get(key, imageId) || {};
return new Promise((resolve, reject) => {
decodePromise.then(imageFrame => {
const imagePlaneModule = getMetaData('imagePlaneModule');
const voiLutModule = getMetaData('voiLutModule');
const modalityLutModule = getMetaData('modalityLutModule');
const sopCommonModule = getMetaData('sopCommonModule');
const isColorImage = isColorImageFn(imageFrame.photometricInterpretation);
// JPEGBaseline (8 bits) is already returning the pixel data in the right format (rgba)
// because it's using a canvas to load and decode images.
if (!isJPEGBaseline8BitColor(imageFrame, transferSyntax)) {
setPixelDataType(imageFrame);
// convert color space
if (isColorImage) {
// setup the canvas context
canvas.height = imageFrame.rows;
canvas.width = imageFrame.columns;
const context = canvas.getContext('2d');
const imageData = context.createImageData(
imageFrame.columns,
imageFrame.rows
);
convertColorSpace(imageFrame, imageData);
imageFrame.imageData = imageData;
imageFrame.pixelData = imageData.data;
// calculate smallest and largest PixelValue of the converted pixelData
const minMax = getMinMax(imageFrame.pixelData);
imageFrame.smallestPixelValue = minMax.min;
imageFrame.largestPixelValue = minMax.max;
}
}
const image = {
imageId,
color: isColorImage,
columnPixelSpacing: imagePlaneModule.pixelSpacing
? imagePlaneModule.pixelSpacing[1]
: undefined,
columns: imageFrame.columns,
height: imageFrame.rows,
intercept: modalityLutModule.rescaleIntercept
? modalityLutModule.rescaleIntercept
: 0,
invert: imageFrame.photometricInterpretation === 'MONOCHROME1',
minPixelValue: imageFrame.smallestPixelValue,
maxPixelValue: imageFrame.largestPixelValue,
render: undefined, // set below
rowPixelSpacing: imagePlaneModule.pixelSpacing
? imagePlaneModule.pixelSpacing[0]
: undefined,
rows: imageFrame.rows,
sizeInBytes: imageFrame.pixelData.length,
slope: modalityLutModule.rescaleSlope
? modalityLutModule.rescaleSlope
: 1,
width: imageFrame.columns,
windowCenter: voiLutModule.windowCenter
? voiLutModule.windowCenter[0]
: undefined,
windowWidth: voiLutModule.windowWidth
? voiLutModule.windowWidth[0]
: undefined,
decodeTimeInMS: imageFrame.decodeTimeInMS,
floatPixelData: undefined
};
// add function to return pixel data
if (imageFrame.pixelData instanceof Float32Array) {
const floatPixelData = imageFrame.pixelData;
const results = convertToIntPixelData(floatPixelData);
image.minPixelValue = results.min;
image.maxPixelValue = results.max;
image.slope = results.slope;
image.intercept = results.intercept;
image.floatPixelData = floatPixelData;
image.getPixelData = () => results.intPixelData;
} else {
image.getPixelData = () => imageFrame.pixelData;
}
// Setup the renderer
if (image.color) {
image.render = cornerstone.renderColorImage;
image.getCanvas = function() {
if (lastImageIdDrawn === imageId) {
return canvas;
}
canvas.height = image.rows;
canvas.width = image.columns;
const context = canvas.getContext('2d');
context.putImageData(imageFrame.imageData, 0, 0);
lastImageIdDrawn = imageId;
return canvas;
};
} else {
image.render = cornerstone.renderGrayscaleImage;
}
// Modality LUT
if (
modalityLutModule.modalityLUTSequence &&
modalityLutModule.modalityLUTSequence.length > 0 &&
isModalityLUTForDisplay(sopCommonModule.sopClassUID)
) {
image.modalityLUT = modalityLutModule.modalityLUTSequence[0];
}
// VOI LUT
if (
voiLutModule.voiLUTSequence &&
voiLutModule.voiLUTSequence.length > 0
) {
image.voiLUT = voiLutModule.voiLUTSequence[0];
}
if (image.color) {
image.windowWidth = 255;
image.windowCenter = 127;
}
// set the ww/wc to cover the dynamic range of the image if no values are supplied
if (image.windowCenter === undefined || image.windowWidth === undefined) {
const maxVoi = image.maxPixelValue * image.slope + image.intercept;
const minVoi = image.minPixelValue * image.slope + image.intercept;
image.windowWidth = maxVoi - minVoi;
image.windowCenter = (maxVoi + minVoi) / 2;
}
resolve(image);
}, reject);
});
}
export default createImage;
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