SPP sharpening exposed ..

Started Jun 3, 2012 | Discussions thread
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xpatUSA
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SPP sharpening exposed ..
Jun 3, 2012

Too much time on my hands today!

I've read that a setting of zero on Sigma Photo Pro's sharpening slider applies some sharpening whether you like it or not. I've read elsewhere that a setting of -0.8 is a bit more like no sharpening. So, having the tools, I fired up the SD10 with an old 50mm macro on it and shot a LO-res pic of my 8*10 ISO target and then looked at the results for various sharpness settings, using QuickMTF.

First the zero setting results:

MTF

Horrible, unless you like lots of artifacts in your pics. Look at the excessive contrast (more than 100%) below (to the left of) 0.25 cycles per pixel! And an MTF of about 50% at the Nyquist frequency is going to provide lots of aliasing for those who like to shoot tiled roofs, picket fences, brick walls, fabric close-ups, you know where I'm heading

Edge Contrast

Now if that ain't sharpened, I don't what is. If you use SPP as a RAW converter and then move on to another application, that's quite a bit of sharpening to take with you! Or, if that was the frequency response of my guitar amp, you're going to need ear-plugs.

Some folk distrust graphs like those above almost as much as political promises. So here's a crop from the pics I took: first for no sharpening and then -0.8 sharpening:

On my non-calibrated monitor, the resultant halos at left are plainly visible and none are seen at right. (both pics were blown up to 700% in PSE and then a screen image captured, cropped and saved as what you see above).

Here are the results for the -0.8 setting:

MTF

A lot smoother but still an MTF of 30% at Nyquist. Some might prefer even less than that and there's plenty of room on the LHS of the slider for them kind of folks (portrait shooters?).

Edge Contrast

Very nice edge, no abrupt changes or insane wriggles. I'd be happy to move that image to PSE with a smidge of unsharp masking waiting in it's future.

I hope this was of interest to those who have wondered (as I did) about the apparent sharpness of images out of SPP.

Why did I shoot in LO res? Because I take web pictures of small objects and just frame and then crop, without re-sampling down.

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Best Regards,

Ted.

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