Sensor linear capture

Take any JPEG and open in Photoshop Elements and convert to 16 bits per channel:

The histogram for this image shows a balanced range of tones, light and dark areas:

The instructions in the course materials were not accurate with my version of elements, however, I found adjust colour curves:

and created a darker image:

to create an image close to how it was originally captured before processing by the camera.  This was achieved by reducing highlights, reducing mid-tone brightness, increasing midtone contrast a reducing shadows.  See also how the histogram has moved dramatically to the left indicating too many dark tones:

I then recreated a normal image by adjusting the curves, mimicking what the camera actually does in processing.  The biggest effect is on the darker parts.

Shot at ISO 100, there was no noise in the original shot as processed by the camera.  I know from experience though that my camera starts producing noise at around ISO 250, so I tend to avoid this unless I deliberately want noise.