CCU

An FFGL effect for Resolume Arena and Avenue. The “video” look of a studio or OB camera comes from a processing chain in a fixed order, each stage a known circuit, and each knob one that a shader turns on the camera control unit's panel. CCU puts those stages in that order, in linear light, and labels the knobs the way a CCU labels them: master gain, white balance, matrix, detail, knee, gamma and black gamma, pedestal, white clip.

What comes out is every badly set-up camera look, and none of it is drawn. Detail adds a high-passed copy made from pixel and line delays, so a hard edge overshoots on one side and undershoots on the other for the width of the delay rather than the width of the edge: that's the halo. Coring keeps detail off the noise, so low coring sharpens the grain and high coring gives the picture a plastic coat. A hue window holds detail back on skin, so faces go soft while the jacket stays sharp. The knee squashes highlights so skies keep their colour; turn it off and they clip, and because the knee comes after white balance, a warm white clips in one channel first. Black gamma lifts the shadows below its level and nowhere else, and the white balance drifts slowly, the way a camera still warming up used to.

Nothing carries over from frame to frame except the drift, an Ornstein-Uhlenbeck walk in double precision on the CPU. The chain is two GLSL passes: the linear pass (linearise, master gain, white balance, matrix) into an RGBA32F buffer, and the process pass (detail, knee, gamma, black gamma, pedestal, white clip, mix) into the host's framebuffer. The OETF is a family with the exponent as the control, and its constants, the matrix and the drift's step are worked out in double once a frame. Every detail tap is a texelFetch, so nothing depends on a texture unit's filtering.

Twenty-three controls in eight groups, each one 0 to 1 as far as the host's concerned, with its null exact in binary: Master Gain from -6 to +18 dB, Master Black and White Clip, R and B gains about green, Drift in mireds, four generic matrix presets and a Saturation, Detail Level and Crispening Freq (the delay, 1 to 9 pixels), H/V Ratio, Coring, Level Dependence, Skin Detail with its hue and width, Knee On, Point and Slope, Gamma and Black Gamma, Mix, and a Show Detail view of the detail signal for setting up.

There's an OpenFX version too, for DaVinci Resolve, Vegas Pro, Nuke and Natron: the same chain and the same controls, rendered on the CPU from the control laws the shader is held to. There the drift is a function of the frame number, so a frame renders the same on its own as it does in sequence.