image-lut

    1.0.4 • Public • Published

    image-lut

    Image Lookup Table library for Node.js

    Install

    $ npm install image-lut
    

    Examples

    See the examples folder or test.js for how to use the image-lut.

    Countries Lookup by Lat/Lon

    countries_small

    An image with the countries of the world is used to look up country names by latitude/langitude. The image has to be equirectangular projected and every country has to have an unique RGB value.

    var ImageLUT = require('image-lut').ImageLUT;
    var lut = new ImageLUT();
     
    var countries = {
        // "R/G/B/A" -> value
        "138/138/138/255": "Luxembourg", 
        "82/82/82/255": "United Kingdom"
    };
     
    lut.init(countries, "../data/countries.png", function (err) {
        // optional, set input domain of image coordinates 
        lut.domain(-180, 180, 83.6341007, -90);
        
        console.log( lut.lookup(6.074,49.787) ); // Luxembourg
        console.log( lut.lookup(0,52) ); // United Kingdom
    });

    (examples/countries.js)

    API

    ImageLUT

    • .init(dict, imagePath, callback)
    • .initSync(dict, imagePath)
    • .domain(xStart, xEnd, yStart, yEnd) optional, like d3.domain to set the input domain of the coordinates of the image
    • .lookup(x,y) -> value
    • .color(x,y) -> [r,g,b,a] array
    • .size() -> image width, hight and channels count
    • .pixel(x,y) -> RBGA values 4 x 8bit encoded into a single number

    Helpers

    • numberToRgb(rgba) -> [r,g,b,a] array
    • rgbToNumber(r, g, b, a) -> rgba number

    Tests

    $ npm install
    $ npm test
    

    Acknowledgments

    Install

    npm i image-lut

    DownloadsWeekly Downloads

    0

    Version

    1.0.4

    License

    none

    Last publish

    Collaborators

    • b-g