An FFGL source that draws test patterns at whatever raster Resolume hands it: SMPTE RP 219 bars, plain 75% and 100% bars, grids, an alignment chart, LED cabinet maps, flat fields, greyscale and a pixel check. Every line is a whole number of pixels and nothing is anti-aliased, so a soft edge on the wall means a scaler somewhere in the chain and never the pattern. It's Test Card's live sibling, with the three things a PNG can't do: a burn-in, a moving marker and a frame counter you can film beside the monitor to read the latency to the frame.
This demo runs the plugin's own C++, compiled to WebAssembly, and its shaders in your browser, so it needs JavaScript and WebGL2. The plugin itself, its source and its downloads are on its repository.