This process mimics the chemical coloring technique favored by Ansel Adams for creating richly toned landscape prints.
1 Convert to Black and White
Start by selecting Enhance > Convert to Black and White, as shown above. Ensure that the monochrome version still retains some contrast, without any large areas of white highlights, as these low-contrast areas will not accept the following tone colors correctly.
2 Color the highlights
In the Color Variations dialog, select Highlights, then click the Decrease Blue thumbnail to make the lighter tones yellow.
3 Color the shadows
Next, select Shadows, then click the Increase Red thumbnail to make the darker tones redder. The image now looks warm in tone.