1 | initial version |
Firstly, you'd better know the gray transformation between gray and rgb: Gray_value = 0.299R + 0.587G + 0.114B, so the transformation is not reversible, the reverse convertion is probably that each channel take the 1/3 of gray value.
Then the convertion may cause information loss due to the format transformation, as I thought.
Hope this can inspire you:)