Hydra blend operations are per-pixel arithmetic on R, G, B values, not layer compositing

When two Hydra signals are combined (add, diff, mult), the operation runs per pixel: for each pixel the RGB values of each source are taken and combined channel by channel. This mirrors the physical display, where each pixel is a cluster of red, green and blue lights and a ‘colour’ is just three brightness values. add sums the channels; diff takes their absolute difference; mult multiplies them. So the results are predictable and physically grounded, e.g. red (1,0,0) plus blue (0,0,1) gives magenta (1,0,1). Jack notes the same pixel-arithmetic logic underlies Photoshop-style blend modes.

Examples

solid(1,0,0).add(solid(0,0,1)).out() gives magenta. solid(1,0,0).mult(solid(0,1,0)).out() multiplies red by green channel-wise, yielding near-black where they don’t overlap.

Assessment

Explain why red + blue reads as magenta under Hydra’s add(). Then predict what diff() of two identical signals produces, and why.