Get the Palette (aka Color Map) for a GeoTIFF
npm install geotiff-palettebash
npm install geotiff-palette
`usage
downloaded GeoTIFF
import { readFileSync } from 'fs';
import { fromArrayBuffer } from 'geotiff';
import { getPalette } from 'geotiff-palette';const data = readFileSync('image.tif');
const arrayBuffer = data.buffer.slice(data.byteOffset, data.byteOffset + data.byteLength);
const geotiff = await fromArrayBuffer(arrayBuffer);
const image = await geotiff.getImage();
const palette = await getPalette(image);
console.log(palette);
palette contains an array of [R, G, B, A] values and looks like this:
javascript
[
[ 112, 108, 96, 255 ], [ 112, 104, 80, 255 ], [ 104, 104, 104, 255 ],
[ 96, 88, 52, 255 ], [ 104, 104, 112, 255 ], [ 128, 120, 108, 255 ],
[ 160, 160, 160, 255 ], [ 152, 152, 144, 255 ], [ 104, 96, 72, 255 ],
[ 96, 80, 44, 255 ], [ 40, 48, 56, 255 ], [ 152, 144, 144, 255 ],
[ 32, 48, 56, 255 ], [ 120, 120, 96, 255 ], [ 112, 120, 104, 255 ],
// ... 256 total items
]
`getting a color
The index number in the palette corresponds to a raster value.
For example, if you have an 8-bit single-band GeoTIFF and you want to get the color for the first pixel with value 130
javascript
const [ band ] = await image.readRasters();
const value = band[0]; // first pixel in the band, which is usually in the top-left of the image
// value is 130
const color = palette[value];
// color is [ 112, 108, 96, 255 ], which is the same as rgba(112, 108, 96, 1)