Separation of the red and blue stellar populations in a spiral galaxy. From left to right we show the original HST colour image of a spiral galaxy in the galaxy cluster Abell 2744, the same colour image after subtraction of the blue component estimated with MuSCADeT, the colour image after subtraction of the red component estimated with MuSCADeT, and the residual image after subtraction of both components. The three first images have the same colour cuts. The residuals are shown with cut levels set to five times the noise level in each colour channel.