Many videos show a band of color gradient of sorts and use it to demonstrate the feature. I want to experiment with various knobs and dials at my own pace and want to use something similar.
How do you create images of these kinds of bands. There are numerous videos, but one example at what I’m looking for is at [ENG] Colour balance rgb - YouTube at around 19th minute.
I’m on Ubuntu, so darktable/gimp instructions would be nice since that is what I have installed right now.