OK. I have more questions.
The following is copied from "AnalogWriteResolution":
analogWriteResolution() is an extension of the Analog API for the Arduino Due.
analogWriteResolution() sets the resolution of the analogWrite() function. It defaults to 8 bits (values between 0-255) for backward compatibility with AVR based boards.
The Due has the following hardware capabilities:
12 pins which default to 8-bit PWM, like the AVR-based boards. These can be changed to 12-bit resolution.
2 pins with 12-bit DAC (Digital-to-Analog Converter)
By setting the write resolution to 12, you can use analogWrite() with values between 0 and 4095 to exploit the full DAC resolution or to set the PWM signal without rolling over.
bits: determines the resolution (in bits) of the values used in the analogWrite() function. The value can range from 1 to 32. If you choose a resolution higher or lower than your board's hardware capabilities, the value used in analogWrite() will be either truncated if it's too high or padded with zeros if it's too low. See the note below for details.
If you set the analogWriteResolution() value to a value higher than your board's capabilities, the Arduino will discard the extra bits. For example: using the Due with analogWriteResolution(16) on a 12-bit DAC pin, only the first 12 bits of the values passed to analogWrite() will be used and the last 4 bits will be discarded.
If you set the analogWriteResolution() value to a value lower than your board's capabilities, the missing bits will be padded with zeros to fill the hardware required size. For example: using the Due with analogWriteResolution(8) on a 12-bit DAC pin, the Arduino will add 4 zero bits to the 8-bit value used in analogWrite() to obtain the 12 bits required."
Why does the "bits" value go from 1 to 32 when the DAC has a 12-bit value? What point is there in having a "bits" value greater than 12?
I'm asking because I read on the internet that an LED's brightness is linear, but the eye's response is not linear. I read about Gamma correcting the brightness of an LED to correspond to the eye's response.
The PWM default is 8-bits. In order to Gamma correct the brightness there would have to be jumps from 0 to 255. It wouldn't be linear from 0 to 255. There would be gaps. However, with 4096 brightness values, maybe the brightness would be more like the eye's response.