S90 Manual shows you can add iContrast after-the-fact in the playback menu
28mm ISO 80 exposure down -2/3 stop to get a little blue in the sky
Original image. iContrast OFF.
ISO 200. Exposure -1.33 stops to bring out the color of the sky, but now foreground is too dark.
Normally exposed image with icontrast medium added in the playback menu
Normally exposed image. iContrast OFF
iContrast on Auto at time of picture capture