Sharpening - When & How much ?

[Guest]

Quite often if I have put an image in the 'Critique Forum' one or two people have commented that the feel the picture had been oversharpened. Now I am not complaining about the criticism, that has to be expected, but to my eye they seem OK. Now the question I ask is, how to determine if a picture needs to be sharpened and if so how much. Also what one considers the correct settings to use in Photoshop or PSP to achieve a reasonable amount of sharpening without overdoing it. ? One further question - what criteria do people use when viewing a picture to form an opinon that it is oversharpened.?

[Ian]

Re: Sharpening - When & How much ?

Hi Dennis, sharpening is a very indefinite thing. Some people prefer more than others. I didn't immediately feel your shot was over-sharpened. Maybe it is, marginally, but it didn't bother me.

Tell tale signs of over-sharpening are (for web display) include edge detail that has broken up or serrated, plus some halo effect, where there is a faint doubel image around sharp edges or other detail. Sharpening also increases visible contrast.

One way to determin critical sharpness is to make several (say 3) copie so of the image sharpened to different levels and then comparing.

For Photoshop Smartsharpen I usually use 20% @1 pixel and then reapply if the first application wasn't enough. If an image was very sharp to start with, it may not need sharpening after resizing at all.

Hope that helps!

Ian

[Guest]

Re: Sharpening - When & How much ?

Many thanks Ian for your views and advice about Photoshop Smartsharpen. I am not sure whether it is available in the earlier version Photoshop CS which I possess. Since I my original posting I have been taking another look at the picture 'Kenmare Estuary' which I posted last week, in view of the comment Vlarcombe made about it's re-sharpening and the sea appearing to have 'exagerated contrast'. Comparing zoomed in views of the image which I posted and with the original it would appear that artifacts have been introduced by the downsizing ready for posting to the forum. Perhaps I am using what may not be the best method to resize, but that raises yet another question. ??

[Autumn]

Re: Sharpening - When & How much ?

Hi Dennis

The picture in question is superb. However, I can the sharpening that some members mentioned. The point at which it is most obvious to me is about one third of the way from the left where the foam is hitting the rocks. It almost looks criss crossed.

No one has told me how much sharpening to use and when I look back on my pictures of about two years ago, I cringe at how much saturation and sharpening I have added.

What I do now, is (if you are using Photoshop) double click the Zoom tool in the palettes (this makes the image viewing at 100%) and then add the sharpening. You can add more and less and see how much at a glance. I keep trying a little bit more. I then view it full screen. I then hold down the Control key and click 'Z' which puts it back to where it was without sharpening. Repeat Control and 'Z' and it brings it back. This way you can compare and you may find you need something in between. I think each picture has to be viewed differently. I don't think that there is a finite answer.

This is just my way. I hope this helps. Anyway it is a lovely picture.

[Kurt]

Re: Sharpening - When & How much ?

Another Photoshop method that I find helpful is to slightly over-sharpen the image then immediately go to Edit>Fade (Shift-Command F on a Mac) where you can remove the sharpening by using the fade slider, I find I can quickly see where problems occur when moving the slider back and forth. This command can be used when making other changes as long as you don't do anything between the original command and the fade.

[Guest]

Re: Sharpening - When & How much ?

Many thanks Autumn and Kurt for those suggestions, I will give them a tryout when I have a Little more time. I feel that I am still searching for the point that the sharpening that I have done is just about right. By the way Autumn, thank you for views on the quality of the picture.

[Patrick]

Re: Sharpening - When & How much ?

Quite often if I have put an image in the 'Critique Forum' one or two people have commented that the feel the picture had been oversharpened. Now I am not complaining about the criticism, that has to be expected, but to my eye they seem OK. Now the question I ask is, how to determine if a picture needs to be sharpened and if so how much. Also what one considers the correct settings to use in Photoshop or PSP to achieve a reasonable amount of sharpening without overdoing it. ? One further question - what criteria do people use when viewing a picture to form an opinon that it is oversharpened.?

There are no golden rules for sharpening, but one thing I have learned it is linked to the size of the image, also the way it is viewed, for example on a monitor, video projector or a print, they will each require slightly different approach.
I personally prefer to sharpen a copy layer that way the image can very easily have the sharpening changed by altering the transparency of the layer.
I also sharpen via channels selecting the most suitable colour channel to apply my sharpening, this method allows more aggressive sharpening but without the halo effect, or at worst reduce it to negligible.
If you want details of this method let me know and I will post it to the forum.
I have done so a number of times in the past, but it may have been before you joined us.

Patrick

[Autumn]

Re: Sharpening - When & How much ?

Kurt, I haven't tried the 'fade' slider for sharpening but I have for other things and it is excellent.

I think it would be a very good idea. So I will try it next time I need to sharpen.

I also used to sharpen by channels. I think I used to just sharpen a desaturated copy and then blend it with the coloured copy. I had forgotten all about that and also how to do it, so please Patrick will you post the instructions.

Audrey

[Patrick]

Re: Sharpening - When & How much ?

Kurt, I haven't tried the 'fade' slider for sharpening but I have for other things and it is excellent.

I think it would be a very good idea. So I will try it next time I need to sharpen.

I also used to sharpen by channels. I think I used to just sharpen a desaturated copy and then blend it with the coloured copy. I had forgotten all about that and also how to do it, so please Patrick will you post the instructions.

Audrey

[Patrick]

Re: Sharpening - When & How much ?


A correction to the Alt+I short cut for inverting should read Crtl+I

Patrick

[Autumn]

Re: Sharpening - When & How much ?

A correction to the Alt+I short cut for inverting should read Crtl+I

Patrick

Thanks Patrick, I have printed the instructions.

[coupekid]

Re: Sharpening - When & How much ?

Many thanks Ian for your views and advice about Photoshop Smartsharpen. I am not sure whether it is available in the earlier version Photoshop CS which I possess. Since I my original posting I have been taking another look at the picture 'Kenmare Estuary' which I posted last week, in view of the comment Vlarcombe made about it's re-sharpening and the sea appearing to have 'exagerated contrast'. Comparing zoomed in views of the image which I posted and with the original it would appear that artifacts have been introduced by the downsizing ready for posting to the forum. Perhaps I am using what may not be the best method to resize, but that raises yet another question. ??

Hi Patrick, it seems everyone has pretty much covered sharpening.

However, with regards to resizing for posting here.

The method I always use, is to use the 'save for web' method in PS.

Here I would advise changing the size to a minimum of 600 pixels on your pictures longest edge, and a maximum of 800. then you can see the file size on the bottom left, from here you can determin the percent of quality, and reduce until the file size is as close (but not over) 250kb for posting here.

The downside is you will lose the exif, but gain a better quality picture.

just ensure you dont save over your original!

I hope I am not teaching you to suck eggs here, but its a method from which I use without too much picture quality loss.

Cheers,
Ben

[Patrick]

Re: Sharpening - When & How much ?

Hi Patrick, it seems everyone has pretty much covered sharpening.

However, with regards to resizing for posting here.

The method I always use, is to use the 'save for web' method in PS.

Here I would advise changing the size to a minimum of 600 pixels on your pictures longest edge, and a maximum of 800. then you can see the file size on the bottom left, from here you can determin the percent of quality, and reduce until the file size is as close (but not over) 250kb for posting here.

The downside is you will lose the exif, but gain a better quality picture.

just ensure you dont save over your original!

I hope I am not teaching you to suck eggs here, but its a method from which I use without too much picture quality loss.

Cheers,
Ben

I use exactly the same method.

As to sharpening pretty well covered, I would say we have just scratched the surface there are many more methods to employ some I know off and as I don't use them have forgotten, and more I don't know about.
As with everything in Photoshop there are always another dozon or so way do do it.

Patrick

[Blithe]

Re: Sharpening - When & How much ?

I have been following this thread with interest and would like to say thank you to both Kurt and Patrick ... I hadn't got as far as using the fade slider in photoshop, or indeed using channels in the way described.... sometimes it just needs someone to point you in the right direction.

[vlarcombe]

Re: Sharpening - When & How much ?

Hi Dennis,

I think most of the sharpening advice has already been given (and is all very sound). The settings and methods I use for sharpening vary pretty much for every picture; the one thing that remains constant is that I always perform the sharpening as the very last operation on a file. I find this particularly important if the image is going to be resized, I always resize before the sharpening.

Vernon.