Pentax K-x review
Like most other digital SLRs, the K-x has highlight and shadow correction features. These do not affect the dynamic range, but they do reduce the brightness of highlight areas and lift shadows.
If you are taking images that you don’t wish to spend too much time editing before printing, it may be worth leaving these settings turned on. However, the shadow correction can introduce noise in shadow areas, so I would recommend using it only at low ISO sensitivities.