Create your Lithophane from JPG via Java

//The original image that needs to be uploaded and the 3d file output after saving
String file = "template.jpg";
String output = "outFile.fbx";

//Create some new parameters
TextureData td= TextureData.fromFile(file);
final float nozzleSize = 0.9f;//0.2mm
final float layerHeight = 0.2f;
float[][] grayscale = ToGrayscale(td);
final float width = 120.0f;//canvas width is 200.0mm
float height = width / td.getWidth() * td.getHeight();
float thickness = 10.0f;//10mm thickness
float layers = thickness / layerHeight;
int widthSegs = (int)Math.floor(width / nozzleSize);
int heightSegs = (int)Math.floor(height / nozzleSize);

//Perform computational operations on Mesh objects
Mesh mesh = new Mesh();
for (int y = 0; y < heightSegs; y++)
{
    float dy = (float)y / heightSegs;
    for (int x = 0; x < widthSegs; x++)
    {
        float dx = (float)x / widthSegs;
        float gray = Sample(grayscale, td.getWidth(), td.getHeight(), dx, dy);
        float v = (1 - gray) * thickness;
        mesh.getControlPoints().add(new Vector4(dx * width, dy * height, v));
    }
}

for (int y = 0; y < heightSegs - 1; y++)
{
    int row = (y * heightSegs);
    int ptr = row;
    for (int x = 0; x < widthSegs - 1; x++)
    {
        mesh.createPolygon(ptr, ptr + widthSegs, ptr + 1);
        mesh.createPolygon(ptr + 1, ptr + widthSegs, ptr + widthSegs + 1);
        ptr++;
    }
}

//Generate 3d scene and save objects
Scene scene = new Scene(mesh);
scene.save(output, FileFormat.FBX7400ASCII);

//The sample method to call
static float Sample(float[][] data, int w, int h, float x, float y)
{
    return data[(int)(x * w)][(int)(y * h)];
}

//ToGrayscale method to call
static float[][] ToGrayscale(TextureData td)
{
    float[][] ret = new float[td.getWidth()][td.getHeight()];
    int stride =td.getStride();
    byte[] data = td.getData();
    int bytesPerPixel = td.getBytesPerPixel();
    for (int y = 0; y < td.getHeight(); y++)
    {
        int ptr = y * stride;
        for (int x = 0; x < td.getWidth(); x++)
        {
            float v = (data[ptr] * 0.21f + data[ptr + 1] * 0.72f + data[ptr + 2] * 0.07f) / 255.0f;
            ret[x][y] = v;
            ptr += bytesPerPixel;
        }
    }
    return ret;
}