`LH` was computed using `dot(-L, H)`, so there needs to be a negative sign when computing `Ht2`. `pdf` is only used for denoising, the change oesn't seem to affect the regression test.
`LH` was computed using `dot(-L, H)`, so there needs to be a negative sign when computing `Ht2`. `pdf` is only used for denoising, the change oesn't seem to affect the regression test.