Digital cameras have revolutionized the way we capture images, but they are not without limitations. While they can capture more visible light than displays can show, they cannot capture all of the available light we can see. To record and manipulate the original camera files (OCF), the data from the camera sensor is converted into a working colour gamut and an opto-electric transfer function (OETF) is applied. The OETF is a digital version of the light from the original scene.
It’s important to note that camera colour gamuts and transfer functions differ from display colour gamuts and transfer functions, as the original camera file contains more information than the display media. This extra colour and tonal detail of the camera profile is crucial for colour grading and VFX.
Digital camera sensors have improved in their ability to capture a wide dynamic range, which is the difference between the darkest shadow detail and the brightest highlights. Standard dynamic range (SDR) only covers six stops and a colour space limited to about 33% of human vision. Video cameras output rec709, because those images were only intended for TV.
Historically, HETV and theatrical releases were shot on film, which captures light logarithmically, greatly increasing its dynamic range. In contrast, digital cameras capture light linearly but convert to log for better use of the bit depth. A log OETF compresses highlights into the top of the data range and uses more bits in the shadows, allowing better detail in dark areas.
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