Under Colour in the Adjust panel, choose a scale. The eye separates colours more easily than greys, so small density differences can stand out.
- grey: the normal radiograph.
- bone: grey with a cool blue tint.
- hot: black through red and yellow to white.
- ironbow: dark blue through purple and orange to white, like a thermal camera.
- viridis: purple through green to yellow, even in brightness.
- rainbow: blue through green to red.
- thermal: high-contrast heat-map colours (also the Thermal preset).
With a colour scale on, a TIFF export is 8-bit colour as displayed rather than 16-bit grey.