negative-darkroom: speed up operation
When getting the CIEXYZ tranmittance back, use these two mathematical identities:
- pow(10, a) * pow(10, b) == pow(10, a+b)
- 1/pow(10, x) == pow(10, -x)
While at it, fix the reference hash, which was broken in commit 3d5e9bc8. (This patch does not alter the hash.)
Edited by Richard B. Kreckel