A figure with an image

Figure 1 shows sin⁡xcos⁡y\sin x \cos y on [0,2π]2[0, 2\pi ]^2 as colour bands. The image, plot.png, is a file in this folder: the preview reads it from there.
plot.png
Figure 1: The function sin⁡xcos⁡y\sin x \cos y: blue below zero, red above.
As Figure 1 shows, the zero set is a grid of lines.