User Manual

For this reason, the C300 Mark II also incorporates the ability to originate very high performance

video in the standardized 4K / UHD formats – at frame rates of 23.98 / 24.00 / 25.0 / 29.97 fps

progressive.

Figure 5 Showing the video processing system to create the 4K / UHD YCbCr 4:2:2 video that is

sent to the XF-AVC codec for recording

9.0 High Dynamic Range (HDR) and Canon Log2

The original Canon Log in the EOS C300 camera was tailored to manage a 12-stop dynamic

range within the constraint of an 8-bit MPEG-2 codec. While in general it worked remarkably

well there were identified limitations in terms of reproducing tonal ranges within deep shadowed

scene segments. The C300 Mark II has a significant extension of dynamic range to 15-Stops –

offering impressive HDR imaging capabilities – and the linear light digital representation for

each of the 2K / HD video components is at a high 14-bit depth. This, in turn, allows for a far

more favorable disposition of digital codes when mapping the nonlinear Opto Electronic

Transfer Function (OETF) – a logarithmic curve termed Canon Log2. It is reproduced in Figure

5. This curve has been carefully designed to ensure an optimum allocation of the output digital

codes to express all of the tonal gradations within dark areas of a scene while simultaneously

faithfully representing the details contained within the highlight areas of that same scene.

The on board recoding in the C300 Mark II has the powerful capability of recording 2K / HD

RGB 444 at a 12-bit or 10-bit depth. Accordingly, the digital coding for various video levels at

both of those bit depths (and the 8-bit level is also included) is listed in Figure 5. The peak

level of 1600% (corresponding to saturation of the image sensor photodiodes) has an IRE level

of 92.7 and the 18% gray reference is at 39.2 IRE. An important extension was made to the

Canon Log2 curve above the peak white level (the maximum level that can be delivered by the

image sensor) – this being a 2-Stop continuation of the transfer function that is intended to

support possible “push-pull” image manipulation in the color grading process.