2d double array to image

Question

I'm currently working on a simulation with continuous agents, which leave a pheromone trail on a 2d double array. The pheromone trails need to be on a 2d array because of a diffusion with a mean filter that needs to be performed. Ultimately, I need to visualise the agents and the pheromone trails, by transforming the double array directly into an awt.Image.

What is the range of values in the 2D double array? You have red, green, and blue values that range from 0 through 255. Create a BufferedImage with the same dimension as your 2D array, convert the 2D double values to a pixel color, and write the pixel color in the same position in the BufferedImage as the 2D array. — Gilbert Le Blanc, Sep 17 '21 at 17:00

user16320675 · Accepted Answer · 2021-09-17T18:05:00.590

Basically create a BufferedImage, as suggested by Gilbert Le Blanc and use its setRGB method to set the pixels (or get its Graphics to draw on it).

Example, assuming values are between 0.0 and 1.0, converting to gray:

private static BufferedImage create(double[][] array) {
    var image = new BufferedImage(array.length, array[0].length, BufferedImage.TYPE_INT_RGB);
    for (var row = 0; row < array.length; row++) {
        for (var col = 0; col < array[row].length; col++) {
            image.setRGB(col, row, doubleToRGB(array[row][col]));
        }
    }
    return image;
}

private static int doubleToRGB(double d) {
    var gray = (int) (d * 256);
    if (gray < 0) gray = 0;
    if (gray > 255) gray = 255;
    return 0x010101 * gray;
}

The doubleToRGB can be changed to use more complicated mapping from value to color.

Example red for lower values, blue for higher:

private static int doubleToRGB(double d) {
    float hue = (float) (d / 1.5);
    float saturation = 1;
    float brightness = 1;
    return Color.HSBtoRGB(hue, saturation, brightness);
}

_{Note: posted code is just to show the idea - can/must be optimized - missing error checking}

^{Note 2: posted mapping to gray is not necessarily the best calculation regarding our perception}

2d double array to image

1 Answers1