Update (1-20): You can now download Crops from the original full sized images by clicking the following links. The Crops were made by IrfanViewer viewed in 100% and then saved as 100% Quality Jpegs, all EXIF preserved:-
| ISO | 200 | 1600 |
| Sharpness -2 |  [Crop1] [Crop2] |  [Crop1] [Crop2] |
| Sharpness 0 |  [Crop1] [Crop2] |  [Crop1] [Crop2] |
| Sharpness +2 |  [Crop1] [Crop2] |  [Crop1] [Crop2] |
| Fine Sharpness -2 |  [Crop1] [Crop2] |  [Crop1] [Crop2] |
| Fine Sharpness 0 |  [Crop1] [Crop2] |  [Crop1] [Crop2] |
| Fine Sharpness +2 |  [Crop1] [Crop2] |  [Crop1] [Crop2] |
Shooting Conditions:-
1. All shots was taken at almost the same time and place; Light source was diffused daylight indoor, Auto White Balance;
2. The camera was mounted on a sturdy tripod, shutter fired with an IR remote controller, SR turned off automatically as such;
3. Lens used is my early Japanese production FA 43/1.9 Limited (Effective Film Focal/AOV: 66.0 mm); Av Exposure Mode at f/5.6 (which should be the sharpest aperture for this lens), Evaluative Metering, +0.3EV Exposure Compensation;
4. Other Settings: AF-S with Central AF Point; Finest JPEG, "Portrait" Custom Image Mode with Default Factory Settings at the Green Dots (the Only Variable is the Sharpness Setting), Shadow Compensation and DR Expansion Off (Factory Defaults), High ISO NR Medium (Factory Default).
How to measurbate?
Just go figure about differences (if any) on edges, textures, details, digital artifacts, noise or even colours and etc., at the camera's real base ISO of 200 and the contemporary typical high ISO of 1600. Well, I test, blog and post, you can decide!
My Observations and Conclusion?
I like Sharpness at Zero (0) myself, which has the best balance of sharpness, details, texture reproduction, and with less digital artifacts. On the other hand, Fine Sharpness does produce sharper details for very high spatial frequency parts of the image, but it promotes noise (especially at higher ISO) and would destroy some details for those moderate high frequency areas (note the purple part of bird in the "Crop2" images).
Well, what I would say the sharpening algorithm of the K-x is much improved over the K-m. With K-m, I would opt to use Fine Sharpness by default instead as "Sharpness" is not that good indeed. This maybe owing to a better sensor used anyway. After all, I am quite satisfied with the default Sharpness setting in the Portrait Custom Image mode (and with the "Bright" mode, I would tune down the Sharpness level a bit).
Read Also:-
K-7 FW 1.02: Sharpness Vs Fine Sharpness Vs Fine Sharpness 2
K-x Different Noise Reduction Settings and Results
My K-m Olive Vs K-x Navy (ISO Measurbation)
12(.3)M Vs 12(.8)M: APS-C K-x Vs FF 5D ISO Measurbation