Gamma in the S2 will most likely be applied as a remap to a developed MEGA file (developing in our software turns the MEGA file into a TIFF). An understanding of gamma is probably in order here. The appropriate application of this type of remap can be particularly efficient, shooting images in a manner that encourages the gamma style remap is generally a good thing to do.
Gamma in a digital file is exactly like gamma in film. Technically, gamma describes a specialized change in transition of tone as a deviation from a gamma of 1.0 (linear), which you will recognize in Photoshop’s Image>Adjust>Curves dialog box when it first opens. Note that our curve does not default to a straight line every time you attempt to apply a curve function; we remember the last curve application and display it every time (as a labor saving device for high volume workflows). Very handy under carefully controlled light.
A gamma of 1.0 displays like the illustration to the left where the straight line (magenta, from corner to corner) describes a linear transition of tone; there is no difference in the width (separation) of any individual tone as compared to any other tone between highlight and shadow. Gamma values in excess of 1.0 are displayed to the left of the magenta straight line as the curved lines running from corner to corner; higher gamma values have larger bends. Gamma has a characteristic where there is an increase in contrast from the shadow to the apex of the bend, and a decrease in contrast from the apex of the bend up to the highlight. This is an important characteristic of gamma, it gains contrast in the shadows and it gives that contrast away in the highlights.
Let’s consider the ramifications of the contrast characteristics of gamma. Our eyes see very small nuances in low values only when the overall illumination is low, like on a moonless night, but we can’t see lots of low values at first. It takes up to 90 minutes to acclimatize our eyesight to very low light levels, but we can see relatively well after we adjust. That same ability to discriminate small differences in reflectance do not exist on a bright, sunlit day because our pupils have “stopped down” to the point where small differences are essentially below threshold, which is why we cannot see extremely low valued transitions in bright light unless the contrast of those low values is greatly expanded. That is why in general, we want to add contrast to areas of the reproduction that are low valued reflectances.
In addition to our eyes inability to distinguish subtle separation in low values under reasonably bright illumination, our ability to visually detect transition of tone in low valued reflectances is further hampered by the reflective target’s difficulty in rendering single percentage points of separation starting up from maximum black. This inability to render what our eyes have difficulty discerning in reasonable illumination further recommends a contrast increase in the shadows. So, the gamma’s characteristic gain in low valued separation falls conveniently to hand as a valuable tool in the shadows. This is a reasonable remap to make on S2 captures. If you’ve shot the image reasonably close to optimum you might be applying a gentle contrast increase in the shadows and a gentle smoothening in the highlights.