Although there is no specified number of measurements for visuals, it is recommended that the number be large enough for the KCMS API library to perform a reasonable interpolation of data for each color channel. The XSolarisVisualGamma() (or colorsense()) module determines the number of intensity levels based on the bits_per_rgb value of the visual (that is, 2 bits_per_rgb). Then it measures every fourth intensity level to speed up measurement. If, for example, it is measuring a 6-bit frame buffer with 64 intensity levels, it performs 17 measurements. For an 8-bit frame buffer, it performs 65 measurements (including intensity 0). For intensity levels that are less than 8 bits_per_rgb, you must skip fewer intensity levels to achieve a more accurate resulting response curve.