Main object is not sharp

Hello everyone. That's my firts post here.

I have a question for the staff/screeners: what do you use to check the sharpening on an uploaded image? Do you have some kind of particular tool or something? I'm asking you that, cause lately I've had many rejections or borderline acceptance, with that kind of comment from the screeners, and in almost every case ( about 80%) the image looked sharp on my screen. I even tried to watch it on different screens. I've tried to add more sharpening (I always work locally on the deatails, with filters) but I've got an awful Moire effect on the edges of details.

I'd really love to solve that problem, I don't know what's wrong with my workflow. Can you help me? Thank you very much.

Enrico

This post has been edited by Martin Krupka on 19th July 2014 - 22:55

Sharpening is a subjective assessment by the screener.

Looking as we do at lots and lots of pictures you develop and eye for it, some screeners are more critical than others.

You would be amazed at how quickly an impression is formed when looking at a picture under screening, sometimes it it a matter of seconds to form an assessment that something is wrong, what takes longer is deciding what is wrong.

One thing to keep in mind is that the human brain is conditioned to look at letters and try to read them, so if those letters are not perfectly formed then this is the first indication that something is wrong with the sharpening. Old style club photographers used to avoid having words in their photos for that very same reason.

Me, I import most photos into Photoshop and run an action to Equalise, check the black and white thresholds and then finally a Levels check. Over sharpening will show the halo on an equalised image, the white threshold will indicate over over exposure, which softens sharpening and the Levels, alt+white triangle will show where the local contrast has been enhanced to form halos. If there is doubt, I may apply Smart Sharpen to the picture to be sure that the picture looks better with more sharpening.

Others screeners screen differently.

On an aside, this link will take to you the best article that I have ever read on the subject of sharpening http://ronbigelow.com/articles/sharpen1/sharpen1.htm

For sharpening to work you need two things:

Good exposure, you just can not sharpen clipped pixels as there is no information there to sharpen. I try and avoid anything above 245 (out of 255 on the Histogram) to be on the safe side. Being able to understand what the Histogram is telling you is essential for a photographer.

Good contrast, sharpening works by boosting the local contrast between to colours to form an edge. Sharpening a dark grey on a lighter grey will not work as effectively as a black and a white.

Lastly it should always be borne in mind that Un-Sharp mask, which to many seems to be the only way they know to sharpen will try to sharpen a plain blue sky, it looks at the subtle variations in hues and then boosts the boundaries between these variations and before you know it you have noise in the sky. You do not have to apply a global sharpening to the picture only the parts that in focus will ever need sharpening.

In retrospect, one reason why you should not exceed 245 in the Histogram means that it makes it harder to clip the boundary between two sharpened edges.

Also, try taking one of your images that is ready for sharpening and really cook the sharpening settings, crank up the radius and amount and see the effect then start reducing these settings until you go completely under sharpened, try this a few times until you get a sharpening setting that works.

Wallace, your answer is just awesome. I think I'll never stop learning. Thank you very much!