1: make the image grayscale.
2: add the filter Map -> Gradient Map to the image.
In this filter's settings, you should see a rectangle that displays a gradient from one color (one "stop") to another. If you click on the stops at the bottom of the rectangle, you can change their opacity and position (from 0% to 100%). If you click on an area between two stops, it adds a new stop. If you double click a stop, it opens a dialog box for you to select the color of the stop.
3: make the stop at the left black with 100% opacity.
4: make the stop at the right white with 100% opacity.
5: add a new stop, and set its position at exactly 50%.
6: double click the new stop and change its color to the tone you want, e.g. red. Then click OK to apply the filter.
7: save the image.
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