Color Space Conversions
Another operation that usually entails all three of the aforementioned types of image degradation is color space conversion. When you convert from a larger gamut to a smaller one, colors present in the source space that are outside the gamut of the destination space get clipped (see Figure 1-7 in the previous chapter for an illustration of gamut clipping).
A significant number of levels also get lost in conversions between spaces with different gammas or tone curves. The bigger the difference between the gammas, the more levels get lost. Figure 2-9 shows what happens when you convert a linear-gamma gradient to a gamma 1.8 working space in both 8-bit/channel and 16-bit/channel modes. Even in 16-bit/channel mode, you see some spikes and holes; in 8-bit/channel mode, about 25 percent of the levels have disappeared.
Figure 2-9 Gamma conversions.