function unique(value, index, self) {
    return self.indexOf(value) === index;
}
Image pixel comparison test script.

 Called by `tasks/test_image.sh in `npm run test-image`.

 CLI arguments:

 1. 'pattern' : glob determining which mock(s) are to be tested

 Examples:

 Run all tests:

     npm run test-image

 Run the 'contour_nolines' test:

     npm run test-image -- contour_nolines

 Run all gl3d image test

     npm run test-image -- gl3d_*