I'm scanning negatives with an Epson and Silverfast software, in raw format.
After inverting the image with command-I, curves and levels are backwards. I could flatten the image, but the size is huge. Is there an alternative?
What I see is that Levels is not reversed, but the Curves default does reverse for Gray Scale images (which is not about inverted, it's true of grayscale either way). There is a menu at the bottom of Curves called Curve Display Options, which has optional reversal, which is called either Light or Ink. Color default is Light, and Grayscale default is Ink, which is reversed, because light is bright, but black ink is dark. But you can change it if you don't like its choice.
If it is color negatives, then it's a serious mistake to not use the scanner softwares Color Negative mode, to properly handle the orange mask in color negatives. Manual inverting to deep blue is simply a worse problem.