Hi, first off, I am not a developer, and I'm not sure if I what I am thinking is entirely correct, so apologies if this makes no sense, but I am trying to understand what's possible in the world of Lightroom plugins...
I use the histogram frequently in Lightroom to adjust exposure and tonality. As I understand it, the Lr histogram is reading the image luminance and color intensity and displaying all those RGB percentages/values in the histogram... is it possible to obtain that image data from Lr for an image, to then perform calculations that could be used in a Lr plugin?
LR has no direct support for a plugin to read the contents of an image accurately. A plugin can get previews of an image, and it can export an image and then read the exported contents. It could export the image as a TIFF and then read the image contents reasonably straightforwardly, but that would not be the exact same contents as the raw image you see in Develop mode. It could export the original raw image, but then it would be very difficult for the plugin to interpret all the different proprietary raw formats.
Thanks for the information Johnrellis, that is helpful to understand.