[libcamera-devel] Sharpness control proposal

[David Plowman]

Hi

We're busy trying to produce libcamera-based alternatives to existing
camera applications. One feature they quite often have is the ability to let
the user change the image sharpness.

I note that V4L2 has a sharpness control, wherein the "minimum value"
means no sharpening, and "larger values increase the amount of
sharpening". Slightly in line with this, I'd like to suggest:

A sharpening control taking a float value, where:
* A value of zero means no sharpening.
* 1.0 applies a "reasonable" default level of sharpening.
* We can stipulate some fairly arbitrary maximum.

Beyond this, we could recommend that the value here is loosely
"proportional" to the amount of sharpening applied. (For the purposes
of this definition, we might refer to the amount of sharpening as
being the difference between a sharpened and unsharpened image.)

What do people think? I feel there is some benefit in trying to be a
bit more prescriptive about what the control means; otherwise it
becomes more difficult for a cross-platform application to know how to
use it.

Best regards
David