D-Log is designed based on opto-electric conversion function characteristics of negative film scan, to be compatible with conventional film workflow.
It covers roughly 15 f-stops’ dynamic range, which is adequate for main stream cinema use while keeping noise acceptable.
The maximum value of the curve depends on the EI value. When EI value is below 1600, the output code value will not reach saturation level (e.g. 1023 for 10bit). This is the necessary compromise to achieve better signal-noise-ratio.
For EI above 1600, the output code value will be beyond saturation level if calculated by the linear-log conversion function, thus an s-shape function is applied to keep output code value in valid range.
D-Gamut is designed to fully utilize capability of DJI Zenmuse camera’s image sensor and at the same time to provide optimal start point for grading.
D-Gamut fully covers ITU-R Rec. 709 and DCI-P3. It has a margin over DCI-P3 so is capable for grading and archiving in cinema use. The RGB primaries of D-Gamut is designed in the way that red, green, blue primaries of D-Gamut are respectively aligned with red, green, blue primaries of DCI-P3 and white point (D65) in a line as much as possible. The benefit is that hue remain mostly unchanged during color space conversion when gamut mapping occurs. For users there are two important advantages: Firstly, manual grading is much easier because contrast and saturation are relatively easier to tune than hue. Secondly, footages before grading have right color so log preview is more meaningful.
The following graph and table show D-Gamut and its RGB primaries. The white point is defined as D65.