Comment by orbital-decay
2 hours ago
In other words, you want either your camera app to select the initial tweaks for you to be able continue in the external editor (not going to happen, RAW editing software is incompatible by design), or your editing software to select the initial tweaks that "look good" (that depends on your software). In RAW mode, Google Camera's output is photometrically correct, even if it stacks multiple frames or denoises it. Which is the only way to do it that makes sense, any other RAW camera app or actual dedicated camera does this the same way.
Or you could provide the RAW and the JPEG and it would start you off at a point that most closely matches the JPEG?
That's exactly what I'm talking about, how do you imagine that working? Metadata is not compatible by design, because processing pipelines are all subtly different and your result will always look different in your editor. Trying to match some basic parameters with the JPEG is possible and some RAW software can do that, but the result is going to be subtly different for the same reason.
Search over all values of all parameters and choose the ones the minimise the mean square error of pixel values.
Obviously that will be slow, so probably do some kind of gradient descent, or perhaps depending on what the parameters are there may be a closed-form solution, I don't know.
Yes the result will be subtly different but it's just a starting point.
I've never had to write such software but in my imagination there is the sensor data, potentially from several exposures, and some static data about the camera, and a list of edits and parameters that the photo app is using to produce the in-camera JPEG. And I just want a way to intervene in that list of edits and parameters to produce my own result. There must be SOME way to do this otherwise how do I edit raws from my real camera? The starting point for camera raw in my photo editor always looks great if the file came from my camera, and always looks ghastly if it came from my mobile.