The Dawn space probe entered orbit around dwarf planet Ceres on March 2015 and continued until 1 November 2018 when its fuel had been depleted. During the Ceres portion of the mission, the spacecraft collected high resolution images and other data.
The color photo from the Dawn mission to Ceres is a combination of high resolution images and separate color image data. It's not a single photo so reduced exposure was not used to produce it. The high resolution images were taken to record the best level of exposure to capture the best possible details.
The Dawn Journal of 31 March 2016 explains how the photo was created.
The high resolution photo of the central feature of Occator Crater is
combined here with color data from the third mapping orbit.
With enhanced color to highlight subtle variations, this illustrates
the red tinge that we described in December. (The scene would not look
this colorful to your eye, even if you and your eye were fortunate
enough to be in a position to see it.)
Here's a more detailed description from the NASA Jet Propulsion Laboratory at PIA20355: Center of Occator Crater (Enhanced Color). The false-color portion of the photo includes near-infrared data invisible to the human eye.
The view was produced by combining the highest resolution images of
Occator obtained in February 2016 (at image scales of 35 meters, or
115 feet, per pixel) with color images obtained in September 2015 (at
image scales of 135 meters, or about 440 feet, per pixel). The three
images used to produce the color were taken using spectral filters
centered at 438, 550 and 965 nanometers (the latter being slightly
beyond the range of human vision, in the near-infrared).