We have made a major development breakthrough enabling real-time Full HD video output via the AXIOM Alpha prototype’s HDMI port. (The final AXIOM camera is planned to have 3G-SDI instead of HDMI interfaces, but for now we are using what is available on the Zedboard development platform). Our current prototype allows us to output progressive 1080p video at up to 60 FPS downscaled from our 4K Super35 image sensor. This represents the completion of a major milestone on our path to the crowd-funding campaign.
While the Alpha prototype is working correctly with a wide range of HDMI monitors and screens tested thus far, we overestimated the compatibility of HDMI field recorders (or rather the combinations of HDMI converters and SDI recorders). So far we have not been able to find a combination of devices that is able to record our HDMI stream, even though we have tested countless different modes and formats that are listed as “compatible” in each device’s manual.
In marketing terms, anything above 8 bit color depth per channel (24 bit RGB) is called “Deep Color”. The HDMI standard has supported it since 2006 with version 1.3 for 10 bit (30 bit RGB/YCrCb) and 12 bit (36 bit RGB/YCrCb). Surprisingly, a lot of (even older) LCDs already support Deep Color - not natively but via FRC and dithering - despite the fact that manufacturers don’t really advertise this feature. The problem is that only high end video cards support deep color HDMI output and each piece of software has to incorporate unique support for it. As deep color is also still a niche application for PC users, driver support issues will almost certainly start piling up. With this aside, the HDMI driver chip on the AXIOM Alpha already supports Deep Color and as we have captured images at up to 12 bit color depth with our selected image sensor, we’ve found ourselves in a strange situation: on monitors supporting deep color, our camera prototype can display more beautiful images and with greater colour fidelity than most PCs.