Change greyscale into colour. It is possible! (Well, kind of…)
Colorizing algorithm: Given a greyscale image and colour seeds or a palette from another image, recode the image in colour. There seem to be various methods to achieve this:
and more recently, these papers (worth reading!):
KS Sim, CP Tso & HY Ting. Canny optimization technique for electron microscope image colourization. Journal of Microscopy, Vol. 232, Pt 2 2008, pp. 313–334.
KS Sim, HY Ting, MA Lai, CP Tso. Improvement to the scanning electron microscope image colourization by adaptive tuning. Journal of Microscopy, Vol 234 (3),2009, pp. 243-250.