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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 | 1x 1x 1x 97x 97x 97x | /**
* Given a low and high window level, return the window width and window center
* Formulas from note 4 in
* https://dicom.nema.org/medical/dicom/current/output/html/part03.html#sect_C.11.2.1.2.1
* extended to allow for low/high swapping
* @param low - The low window level.
* @param high - The high window level.
* @returns a JavaScript object with two properties: windowWidth and windowCenter.
*/
function toWindowLevel(
low: number,
high: number
): {
windowWidth: number;
windowCenter: number;
} {
// Allow for swapping high/low
const windowWidth = Math.abs(high - low) + 1;
const windowCenter = (low + high + 1) / 2;
return { windowWidth, windowCenter };
}
/**
* Given a window width and center, return the lower and upper bounds of the window
* The formulas for the calculation are specified in
* https://dicom.nema.org/medical/dicom/current/output/html/part03.html#sect_C.11.2.1.2.1
* if (x <= c - 0.5 - (w-1) /2), then y = ymin
* else if (x > c - 0.5 + (w-1) /2), then y = ymax
* else y = ((x - (c - 0.5)) / (w-1) + 0.5) * (ymax- ymin) + ymin
* @param windowWidth - the width of the window in HU
* @param windowCenter - The center of the window.
* @returns a JavaScript object with two properties: lower and upper.
*/
function toLowHighRange(
windowWidth: number,
windowCenter: number
): {
lower: number;
upper: number;
} {
const lower = windowCenter - 0.5 - (windowWidth - 1) / 2;
const upper = windowCenter - 0.5 + (windowWidth - 1) / 2;
return { lower, upper };
}
export { toWindowLevel, toLowHighRange };
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