geotiff
Version:
GeoTIFF image decoding in JavaScript
97 lines • 4 kB
JavaScript
export function fromWhiteIsZero(raster, max) {
const { width, height } = raster;
const rgbRaster = new Uint8Array(width * height * 3);
let value;
for (let i = 0, j = 0; i < raster.length; ++i, j += 3) {
value = 256 - (raster[i] / max) * 256;
rgbRaster[j] = value;
rgbRaster[j + 1] = value;
rgbRaster[j + 2] = value;
}
return rgbRaster;
}
export function fromBlackIsZero(raster, max) {
const { width, height } = raster;
const rgbRaster = new Uint8Array(width * height * 3);
let value;
for (let i = 0, j = 0; i < raster.length; ++i, j += 3) {
value = (raster[i] / max) * 256;
rgbRaster[j] = value;
rgbRaster[j + 1] = value;
rgbRaster[j + 2] = value;
}
return rgbRaster;
}
export function fromPalette(raster, colorMap) {
const { width, height } = raster;
const rgbRaster = new Uint8Array(width * height * 3);
const greenOffset = colorMap.length / 3;
const blueOffset = (colorMap.length / 3) * 2;
for (let i = 0, j = 0; i < raster.length; ++i, j += 3) {
const mapIndex = raster[i];
rgbRaster[j] = (colorMap[mapIndex] / 65536) * 256;
rgbRaster[j + 1] = (colorMap[mapIndex + greenOffset] / 65536) * 256;
rgbRaster[j + 2] = (colorMap[mapIndex + blueOffset] / 65536) * 256;
}
return rgbRaster;
}
export function fromCMYK(cmykRaster) {
const { width, height } = cmykRaster;
const rgbRaster = new Uint8Array(width * height * 3);
for (let i = 0, j = 0; i < cmykRaster.length; i += 4, j += 3) {
const c = cmykRaster[i];
const m = cmykRaster[i + 1];
const y = cmykRaster[i + 2];
const k = cmykRaster[i + 3];
rgbRaster[j] = 255 * ((255 - c) / 256) * ((255 - k) / 256);
rgbRaster[j + 1] = 255 * ((255 - m) / 256) * ((255 - k) / 256);
rgbRaster[j + 2] = 255 * ((255 - y) / 256) * ((255 - k) / 256);
}
return rgbRaster;
}
export function fromYCbCr(yCbCrRaster) {
const { width, height } = yCbCrRaster;
const rgbRaster = new Uint8ClampedArray(width * height * 3);
for (let i = 0, j = 0; i < yCbCrRaster.length; i += 3, j += 3) {
const y = yCbCrRaster[i];
const cb = yCbCrRaster[i + 1];
const cr = yCbCrRaster[i + 2];
rgbRaster[j] = y + 1.402 * (cr - 0x80);
rgbRaster[j + 1] = y - 0.34414 * (cb - 0x80) - 0.71414 * (cr - 0x80);
rgbRaster[j + 2] = y + 1.772 * (cb - 0x80);
}
return rgbRaster;
}
const Xn = 0.95047;
const Yn = 1.0;
const Zn = 1.08883;
// from https://github.com/antimatter15/rgb-lab/blob/master/color.js
export function fromCIELab(cieLabRaster) {
const { width, height } = cieLabRaster;
const rgbRaster = new Uint8Array(width * height * 3);
for (let i = 0, j = 0; i < cieLabRaster.length; i += 3, j += 3) {
const L = cieLabRaster[i + 0];
const a_ = (cieLabRaster[i + 1] << 24) >> 24; // conversion from uint8 to int8
const b_ = (cieLabRaster[i + 2] << 24) >> 24; // same
let y = (L + 16) / 116;
let x = a_ / 500 + y;
let z = y - b_ / 200;
let r;
let g;
let b;
x = Xn * (x * x * x > 0.008856 ? x * x * x : (x - 16 / 116) / 7.787);
y = Yn * (y * y * y > 0.008856 ? y * y * y : (y - 16 / 116) / 7.787);
z = Zn * (z * z * z > 0.008856 ? z * z * z : (z - 16 / 116) / 7.787);
r = x * 3.2406 + y * -1.5372 + z * -0.4986;
g = x * -0.9689 + y * 1.8758 + z * 0.0415;
b = x * 0.0557 + y * -0.204 + z * 1.057;
r = r > 0.0031308 ? 1.055 * r ** (1 / 2.4) - 0.055 : 12.92 * r;
g = g > 0.0031308 ? 1.055 * g ** (1 / 2.4) - 0.055 : 12.92 * g;
b = b > 0.0031308 ? 1.055 * b ** (1 / 2.4) - 0.055 : 12.92 * b;
rgbRaster[j] = Math.max(0, Math.min(1, r)) * 255;
rgbRaster[j + 1] = Math.max(0, Math.min(1, g)) * 255;
rgbRaster[j + 2] = Math.max(0, Math.min(1, b)) * 255;
}
return rgbRaster;
}
//# sourceMappingURL=rgb.js.map