rascar wrote:What is meant by "re-assigned colors?
What is the process involved?
Though I did not uncover the specifics, I did find that this image was photographed through the following Hubble ACS camera filters, and the names encode the wavelength and the bandwidth of the filter:
F435W (B) - Wideband visual blue/indigo
F502N ([O III]) - Narrowband visual green/teal (optimized to measure ionized oxygen emissions)
F555W (V) - Wideband visualyellow-green
F658N (Halpha + [N II]) - Narrowband visual deep red (optimized to meaure ionized hydrogen emissions)
F814W (I) - Wideband near infrared
Notably, since one of the colors is not actually visible to the naked eye, some mapping of this color spectrum to the one we CAN see and represent in images had to be done. The image assembly from individual datasets was likely done in Photoshop, and the captured color spectrum was probably compressed so that near infrared data contributed a deep red color to the image, the red data contributed a more orange color, etc. I'll add that without having done the processing or having read an account of it it's impossible to say for sure how it was processed.
There is good information at the page the "
released" link in the caption leads you to.
-Noel