Histogram combing is a phenomenon that digital photographers want to avoid whenever possible. Histogram combing occurs when an already processed file is adjusted. This phenomenon is one way to illustrate how important it is to use a calibrated and profiled monitor to edit Raw files you plan to send to a lab for printing.
The dog food distribution is missing something—results near the average. If a customer receives this kind of distribution, someone else is receiving a heart cut, and the customer is left with the “dog food,” the odds and ends left over after the master’s meal.
Likewise the histogram range is measuring the peak to peak jitter. Note that the peak to peak jitter only has meaning when referenced to the total number of measurements included because the random jitter component is unbounded and increases with increasing the number of measurements. In our example the total population is shown in the Number of measurements in the P1 statistics, 1.342376E^6 in Figure 9.
Normal. A common pattern is the bell–shaped curve known as the “normal distribution.” In a normal distribution, points are as likely to occur on one side of the average as on the other. Be aware, however, that other distributions look similar to the normal distribution. Statistical calculations must be used to prove a normal distribution.