The image was created from Hubble data from proposal 12440: S. Faber (University of California, Santa Cruz) and H. Ferguson (STScI) et al.
WFC3/IR F125W (J), ACS/WFC F606W (V), and F814W (I)
This image is a composite of separate exposures acquired by the WFC3 and ACS instruments on HST. Several filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are:
Red: F125W (J)
Blue: F606W (V)
Green: F814W (I)