True Sharpness vs Fake Sharpness article

[benny]

Came across this in Clubsnap and thought some of you guys might be interested.

Excerpt:

True detail vs. fake sharpness
13th December 2007, 12:41 pm

It’s the same on every web forum - if you post a digital picture which would be acceptable to a photo library or professional buyer, half a dozen grumpy one-liners will come out saying ‘That don’t look sharp to me’ or ‘there must be something wrong with your XXX’ (fill in D300, A700, E-3, D3, 40D as required). Then someone posts a hugely messed up image and people say ‘Wow! What sharpness!’…


What is happening here? Why do some people know how to see fine detail rendering in an unprocessed image, while others do not see something as sharp until you can count the jaggies on every hair and see a halo round every white to black edge transition? There are several factors. One may simply be the type of screen used to view the image. We use Apple Mac Cinema screens throughout - two 24 inch, three 20 inch. They have the same technology as the LG branded screens used by Alamy to check image submissions. They are very neutral, adding no sharpening of their own, and very crisp with no anti-aliasing of images. The Mac system permits anti-aliasing of text and offers four levels of softening, which you can pick to suit various types of LCD and CRT screen. But some graphics cards also anti-alias images, and some screens - especially CRT monitors - are inherently very soft. When we used CRT monitors, we always specified Mitsubishi Diamondtron because they gave the most accurate pixel for pixel view of digital images.

Read the rest of the article...

Which is sharper to you?



or

[hwchoy]

even they worry about diffraction softness!

[luenny]

That's one good article Benny, thumbs up!

But one thing I don't really understand is how this unsharp mask work. I often find that after just doing unsharp mask for picture to be posted often produce pictures that are not that edgy. To really get the edge, sometimes I have to do a sharpen after doing unsharp mask. I know this is part of image processing but does anybody know what unsharp mask is doing differently from normal sharpen? Thanks.

[valice]

Besides USM, there is also another method to do something similar like USM which basically tries to improve the contrast in the transitions of the edges like you already know.

You can try using High Pass filtering as well. A faster method which I tend to use over USM.

[StanChung]

Great article Benny, good to know especially since I plan to do some poster project soon.

I'm too used to seeing aquajournals so I do over sharpen quite a bit then fade as necessary. Not the best method but for web it's really not critical IMHO.


For or use USM, I normally use 80%, radius 1 or 2 depending on size of the image.
If the shot is not sharp in the 1st place I'd just reshoot if possible!