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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 378944x 378944x 33x | import now from './now';
import { IImage } from '../../../../types';
/**
* This function transforms stored pixel values into a canvas image data buffer
* by using a LUT. This is the most performance sensitive code in cornerstone and
* we use a special trick to make this go as fast as possible. Specifically we
* use the alpha channel only to control the luminance rather than the red, green and
* blue channels which makes it over 3x faster. The canvasImageDataData buffer needs
* to be previously filled with white pixels.
*
* NOTE: Attribution would be appreciated if you use this technique!
*
* @param {Image} image A Cornerstone Image Object
* @param {Array} lut Lookup table array
* @param {Uint8ClampedArray} canvasImageDataData canvasImageData.data buffer filled with white pixels
*
* @returns {void}
* @memberof Internal
*/
export default function (
image: IImage,
lut: Uint8ClampedArray,
canvasImageDataData: Uint8ClampedArray
): void {
let start = now();
const pixelData = image.getPixelData();
image.stats.lastGetPixelDataTime = now() - start;
const numPixels = pixelData.length;
const minPixelValue = image.minPixelValue;
let canvasImageDataIndex = 3;
let storedPixelDataIndex = 0;
// NOTE: As of Nov 2014, most javascript engines have lower performance when indexing negative indexes.
// We have a special code path for this case that improves performance. Thanks to @jpambrun for this enhancement
// Added two paths (Int16Array, Uint16Array) to avoid polymorphic deoptimization in chrome.
start = now();
Iif (pixelData instanceof Int16Array) {
if (minPixelValue < 0) {
while (storedPixelDataIndex < numPixels) {
canvasImageDataData[canvasImageDataIndex] =
lut[pixelData[storedPixelDataIndex++] + -minPixelValue]; // Alpha
canvasImageDataIndex += 4;
}
} else {
while (storedPixelDataIndex < numPixels) {
canvasImageDataData[canvasImageDataIndex] =
lut[pixelData[storedPixelDataIndex++]]; // Alpha
canvasImageDataIndex += 4;
}
}
} else Iif (pixelData instanceof Uint16Array) {
while (storedPixelDataIndex < numPixels) {
canvasImageDataData[canvasImageDataIndex] =
lut[pixelData[storedPixelDataIndex++]]; // Alpha
canvasImageDataIndex += 4;
}
} else Iif (minPixelValue < 0) {
while (storedPixelDataIndex < numPixels) {
canvasImageDataData[canvasImageDataIndex] =
lut[pixelData[storedPixelDataIndex++] + -minPixelValue]; // Alpha
canvasImageDataIndex += 4;
}
} else {
while (storedPixelDataIndex < numPixels) {
canvasImageDataData[canvasImageDataIndex] =
lut[pixelData[storedPixelDataIndex++]]; // Alpha
canvasImageDataIndex += 4;
}
}
image.stats.lastStoredPixelDataToCanvasImageDataTime = now() - start;
}
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