Sharpening

[jfa]

Initially I hesitated to raise the perennial question on sharpening but then remembered my signature motto so here goes.

I am curious to know what tools people are using and are happy with to sharpen an image? Or are you all happy with Photoshops unsharpen, high pass, low pass, and so on tools?

[Lin Evans]

Hi John,

There are essentially two types of "sharpening" (with a number of variables) for images. Which to use and when depends on "why" the image is not sharp and how we want it to appear.

If the image simply needs a bit of "unsharp mask" whether selectively or uniformly across the image, I just use photoshop's "unsharp mask." Unsharp mask actually is an edge contrast enhancement tool which differentially raises contrast at edge boundaries between dark and light pixels. This is somewhat akin to using an ink pen to "outline" some text to "set it off" and draw the eyes to these boundaries. This makes the image appear "sharper" but really is not true sharpening. We must use care in how many pixels we darken or lighten at edge boundaries or we have issues of "halos" around our images. If you see a white "ghost" near dark boundaries or a dark "ghost" surrounding light boundaries it's usually a sure indication of over zealous use of unsharp masking. Photoshops regular "sharpen" (as opposed to Unsharp Mask) doesn't discriminate at edge boundaries but simply enhances adjacent pixel contrast. This can lead to a very "oversharpened" look which most do not like. There are a host of sharpening algorithms available which actually go beyond what Photoshop does. Some are better at some types of images than others and experimentation is often the only way to determine which is best for a particular image.

To understand how true sharpening is accomplished we need to understand a bit about how digital image detail boundaries are created. To imagine this, consider that we could create a featureless disc which was pure white (255, 255, 255 RGB values) and place it on a pure black backdrop which is also essentially featureless and smooth with a value of (00, 00, 00 RGB). At the boundary edge of the white disc, we will find a number of pixels (perhaps four or even five) which range from pure black to increasingly lighter shades of grey to white.

True sharpening is done by algorithms collectively know as "deconvolution." What deconvolution does is find detail boundaries and actually change the number of these edge boundary pixels which effectively "sharpens" the edge by reducing the number of gradations in these edge pixels.

Because of the ability to actually shift, add and delete pixels selectively, deconvolution algorithms can also correct for motion blur to as many as 20 pixels or so. So these algorithms are used by forensic science to do things like read license plates which are motion blurred, etc.

Obviously, it's not possible to do miracles with deconvolution, but it is possible to save otherwise useless photos which either suffer from out of focus or motion blur and truly "sharpen" detail edge boundaries.

One software I use for this purpose is called "Focus Magic." Focus Magic combines a little Unsharp Mask with deconvolution and does a very nice job in many cases.

You can see Focus Magic here:

http://www.focusmagic.com/

This software works both as a stand-alone product and as a Photoshop Plug-In.

Best regards,

Lin

[Ronniebootwest]

What an in depth technical reply from Lin - very interesting and thank you for the very full explanation.

For my part, I still think that, for general sharpening, the 'Lab Color' method takes a lot of beating. There are so many programs that

claim to be expert at everything to do with sharpening, but for general use I still use Photoshop for most of me sharpening needs.

Ron

[davegee]

I use a mixture of "high pass" sharpening and "unsharp mask".

When I have finished editing I create a new layer with my merged down, edited image in it. I create a high pass sharpening layer above that and then apply unsharp mask to the merged layer.

It is then possible to alter the opacity of both these layers to produce the desired result.

Layer masks also allow for selective sharpening.

DaveG

[Henri.R]

There are essentially two types of "sharpening" (with a number of variables) for images. Which to use and when depends on "why" the image is not sharp and how we want it to appear.

Hi Lin,

Thanks a lot for your comprehensive explanation, very useful for all of us..

I remember somewere Igor warned for sharpening in connection to the moire-effect during zooming; maybe you can tell more on this subject?

regards,

Henri.

[xahu34]

... True sharpening is done by algorithms collectively know as "deconvolution." ...

As of version 9 (CS2) Photoshop includes sharpening based on deconvolution: Filter > Sharpen > Smart Sharpen.

Regards,

Xaver

[fh1805]

I use only Unsharp Mask in Photoshop Elements and with parameters suggested by, if memory serves me right, Barry Beckham in a post a couple of years ago: Radius 0.3 pixels, Threshold 1, Percentage to suit taste (most of the time I'm in the range 100-250%)

regards,

Peter

[mbskels]

I am curious to know what tools people are using and are happy with to sharpen an image? Or are you all happy with Photoshops unsharpen, high pass, low pass, and so on tools?

John

I have used 'The Light's Right' Professional Sharpening Toolkit which is currently a set of PS Scripts for several years. I find them by far the most flexible sharpening procedures around. The toolkit comes with comprehensive manual and series of examples in the use of the scripts.

Particular advantages are that the sharpening is applied in separate stages (after capture and prior to print) - with an additional option (creative sharpening) where local sharpening is required. The sharpening is also layer based and can therefore be stored with the image and tweaked at a later date.

The scripts can be used in automatic mode (click and go) or advanced mode which enables a high degree of control over the level/type of sharpening applied.

Thoroughly recommend them. They are made available free of charge but a donation is requested if you find them useful.

They are at http://www.thelightsright.com/view/PhotoshopTools?page=2

Malcolm

[Maureen]

Now use sharpening on the Raw file in Lightroom or CS4.

Previous versions before Raw, I always created a new layer, used ALT merge visable which changed the new layer into a flattened version as a layer and then sharpened that layer, so all the original work was untouched below.

I could then save the edited image with the sharpened layer above as a PSD file.

If I felt it was over done I could go back, delete the sharpened layer, and simply create another new layer, ... alt merge visable and use the unsharp mask again.

Great explanation Lin. Thanks.

Katrin Eismann has a great book which has very good advice about sharpening.

I would be very hesitant about giving out sharpening settings as a quick fix as they can vary so much from image to image, you would not generally use the same settings for portraits as landscapes.

Often best to select an area to sharpen in the image. maybe use the lazy lasso and feathering.

Hope this helps,

[jfa]

Lin

Thanks for the concise and very informative overview on sharpening, I always learn something from you explanations, I am testing Focus Magic which appears to be a powerful and useful tool.

PS Not sure if you have updated your personal avatar or I am not very observant but I like the image.

Maureen

Your description on how you worked before using the raw files in Lightroom or CS4 is precisely the same as my current method of working in this area as I am still working in CS3. The ALT merge visable command to save the merged layer with all working layers in tact is an excellent way to preserve ones work in photoshop and I do this on all files I work on sharpening or otherwise.

Malcolm

Thanks for the link to 'The Light's Right' Professional Sharpening Toolkit. I have downloaded the scripts and I will give them a try.

The site is a wealth of information particular the tutorials, well worth a look for anyone.

Thanks everyone for your replies, my aim was to see what people were doing in this area and if tools had changed much from the days when I used FocalBlade, Sharpener Pro, Focus Magic and others.

[Ed Overstreet]

Again different strokes for different folks.

For PTE I do most of my slide editing directly on the Nikon NEF (RAW) file in Nikon Capture NX2. After resizing the image accordingly and setting the view at 100% magnification, I use Capture's excellent Unsharp Mask, generally with the Amount set for 50%, the Radius between 3 and 5 depending on how the image looks on the screen when I play with it, and the Threshold at 0. For images in which I'm concerned that sharpening might increase noise in solid-colour areas (with high ISOs), I use the nifty little trick (I forget now where I got this trick, not I think from Nikon) of using the High Pass Filter with the mode switch set for Luminance/Chrominance, the Chrominance set at 0% and Luminance at 100%, and the blend mode set for Overlay, then adjust the radius to taste. This does an excellent job of sharpening only the edges without affecting those solid areas that would be prone to noise increases under sharpening. (By the way the same trick doesn't seem to work with Photoshop's High Pass filter, I've tried it and the results I got were awful.)

The other choice in Capture NX2 for protecting solid areas from noisy sharpening is to use the U-point controls with the Unsharp Mask selectively to protect those areas. However I find the High Pass approach is faster and easier to use, if you want to limit sharpening to edges and protect pixels in broader areas. (You can also play with the Unsharp Mask's Threshold slider to try to limit sharpening to edges, but I often find that increasing the Threshold tends to reduce the edge sharpening more than I'd prefer in many images. But this is another thing to try if nothing else seems to work the way you prefer.)

When I edit in Photoshop (usually only for prints), I always sharpen with Nik Sharpener Pro 3, following the manual's advice. For slides for PTE, when I (rarely) edit those in Photoshop, I use NSP3's "Display" algorithm, which works great for monitor or projection displays. (I verified with Nik tech support that Display is what they recommend for images intended for projection). BTW I find NSP3 does SUPERB sharpening for prints, enabling me to judge with the on-screen proof mode what to use for printing -- I find this works MUCH better for me than Photoshop's Unsharp Mask, and the interface and decisions you make for printing are logical, simple and user-friendly. You also have access to the U-point selection tools in the filter, if you feel the need to protect specific areas of the photo from sharpening. And NSP3 comes in editions for Lightroom and Aperture as well as Photoshop, but not alas for Capture NX2 (I've suggested this to them) which is why I do all my print editing in Photoshop even though I do almost all slide editing in Capture -- for the sharpening.

Always resize the image for whatever pixel dimensions you'll use for your final output before sharpening with any tool, not after. (I make the same recommendation for noise reduction on an image, even though I know lots of supposed experts disagree with me on this. Noise reduction and sharpening always affect each other and involve a trade-off to the photographer's taste, and the results of the appearance of the trade off very much depend on the image resolution/pixel dimensions, if you're making that judgment visually on the monitor I think it is stupid to argue that noise reduction should be done before, rather than after, resizing, as I've seen some writers recommend. But, thank God, I'm not them and they aren't me, again different strokes for different folks.

As always, you will get a range of opinions and advice, and in almost everything in photography there is never a single "right" or "wrong" solution to any technical or artistic issue, IMO. For whatever it's worth, these are my views, feel free to use or ignore at will

[Guest Yachtsman1]

Hi Ed

Harping back to your previous projector problems, I've always steered clear of sharpening images for PTE because of previous comments on here about moire shimmering & stuttering in animation. Have you tried using the said projector with straight images no sharpening?

Regards Eric

Yachtsman1.

[Peter S]

The late Bruce Fraser is widely considered as one of the leading experts on sharpening and his work has been carried on by Jeff Schewe and incorporated into recent versions of Lightroom and Photoshop.

If you follow the link below and then read the thread you will find a good explanation of the three types of sharpening you can use to perfect your images.

http://luminous-landscape.com/forum/index....st&p=288501

Also look at this thread Jeff Schewe is producing a new book.

http://luminous-landscape.com/forum/index....st&p=289256

If you have not visited the Luminous Landscape web site before I would recommend it as a great source of info on many aspects of photography including Lightroom and Photoshop.

http://www.luminous-landscape.com/

Kind regards

Peter

[Ed Overstreet]

Hi Ed

Harping back to your previous projector problems, I've always steered clear of sharpening images for PTE because of previous comments on here about moire shimmering & stuttering in animation. Have you tried using the said projector with straight images no sharpening?

Regards Eric

Yachtsman1.

Hi Eric. Interesting question. No I haven't. But I've had many shows projected on the same projector and in the same room over the past few years, all with sharpened images, and I've never seen any shimmering or stuttering on my shows except for that one panorama panning problem that JRR and I have reported elsewhere on this Forum. So I don't think our problem is sharpening-related.

I know there is a danger of over-sharpening images; I always base my sharpening for PTE on a visual judgment of the results on my CRT monitor with the slide viewed at 100% magnification. I especially pay attention to fine lines or high-contrast borders in or near the sky (e.g., pesky hydro and telephone wires, when I haven't edited them out of the picture or couldn't) to make sure I don't see any haloing around them, and if I do, to scale back either the amount or the radius of the sharpening.

I mention CRT, versus LCD, by the way, because recently JRR and I have noticed that on some shows (the one where I spotted this was one of Peter Cole's sequences) we can see banding in the sky on an LCD monitor that doesn't appear on my CRT monitor but does on my laptop's LCD, using the same video card and resolution. (I've suggested to Jim that he maybe post a new thread on this, since he discovered the problem and I confirmed it, but he and Gwen are out of town for a few more weeks so it may be a little while yet.) I almost never edit photos or display PTE shows on my laptop's LCD monitor, I use my CRT exclusively except on the very rare occasion when I'm traveling with my laptop, or if there's a power outage at home and I feel the need to do something that I can finish while the laptop battery still has a charge.) I also noted on the thread about JPG sizing and compression that banding that others on the thread were seeing in an example on their (presumably LCD) monitors, I wasn't seeing on my CRT monitor. I'm not sure why this would be, and this is rather off-topic but not really, as it might also affect one's perception of sharpening. Next time I do some sharpening of new images (I'm currently up to my elbows in old images) I'll make a point of comparing the results on my CRT monitor (hooked to my laptop) and the laptop's LCD monitor to see if that matters. If it does, I'll try to remember to post something about what I find on this thread.

[cjdnzl]

Hi Eric. Interesting question. No I haven't. But I've had many shows projected on the same projector and in the same room over the past few years, all with sharpened images, and I've never seen any shimmering or stuttering on my shows except for that one panorama panning problem that JRR and I have reported elsewhere on this Forum. So I don't think our problem is sharpening-related.

I know there is a danger of over-sharpening images; I always base my sharpening for PTE on a visual judgment of the results on my CRT monitor with the slide viewed at 100% magnification. I especially pay attention to fine lines or high-contrast borders in or near the sky (e.g., pesky hydro and telephone wires, when I haven't edited them out of the picture or couldn't) to make sure I don't see any haloing around them, and if I do, to scale back either the amount or the radius of the sharpening.

I mention CRT, versus LCD, by the way, because recently JRR and I have noticed that on some shows (the one where I spotted this was one of Peter Cole's sequences) we can see banding in the sky on an LCD monitor that doesn't appear on my CRT monitor but does on my laptop's LCD, using the same video card and resolution. (I've suggested to Jim that he maybe post a new thread on this, since he discovered the problem and I confirmed it, but he and Gwen are out of town for a few more weeks so it may be a little while yet.) I almost never edit photos or display PTE shows on my laptop's LCD monitor, I use my CRT exclusively except on the very rare occasion when I'm traveling with my laptop, or if there's a power outage at home and I feel the need to do something that I can finish while the laptop battery still has a charge.) I also noted on the thread about JPG sizing and compression that banding that others on the thread were seeing in an example on their (presumably LCD) monitors, I wasn't seeing on my CRT monitor. I'm not sure why this would be, and this is rather off-topic but not really, as it might also affect one's perception of sharpening. Next time I do some sharpening of new images (I'm currently up to my elbows in old images) I'll make a point of comparing the results on my CRT monitor (hooked to my laptop) and the laptop's LCD monitor to see if that matters. If it does, I'll try to remember to post something about what I find on this thread.

Ed,

Most, if not all LCD panels on laptops - and a lot of larger units - display images as a 6-bit image, that is only 64 steps between black and white, and banding is accentuated because of this. Intermediate colors are dithered to recreate the effect of an 8-bit image. CRTs are analog and can handle 8, 16, or even 32-bit images with no trouble, but LCDs cannot, except for the very high-priced professional graphics units.

Colin

[Guest Yachtsman1]

Hi Ed

From my own experience, my problems with unstable animated images came on with 5.6, I appear to have overcome them by switching off my laptop screen when using a projector. So in my estimation my equipment has reached its usuable limits. If you removed the sharpening from your problem sequence and reported the results it could prove useful.

Regards Eric.

[davegee]

.....or apply selective sharpening to offending images.

Don't sharpen trees (lots of detail) or skies etc.

DaveG

[jfa]

Thanks Peter some useful information in the suggested links.

As of version 9 (CS2) Photoshop includes sharpening based on deconvolution: Filter > Sharpen > Smart Sharpen.

Anyone have any comments on how effective this tool has been for them?

[Ed Overstreet]

Ed,

Most, if not all LCD panels on laptops - and a lot of larger units - display images as a 6-bit image, that is only 64 steps between black and white, and banding is accentuated because of this. Intermediate colors are dithered to recreate the effect of an 8-bit image. CRTs are analog and can handle 8, 16, or even 32-bit images with no trouble, but LCDs cannot, except for the very high-priced professional graphics units.

Colin

That's interesting, thanks Colin. I think you've helped me decide what desktop monitor I'm getting whenever my 9-year-old Trinitron CRT finally dies or has dimmed to the point where I can't calibrate correctly any more. I don't think it's going to be an LCD display. Yes they take less space, but my desk has been configured nicely to work around my 19" CRT so as long as I don't go into a much larger size (and I'm quite happy with the 19") I don't see any reason for me to switch to an LCD desktop, and you've just given me a good reason not to switch.

[Ed Overstreet]

Hi Ed

From my own experience, my problems with unstable animated images came on with 5.6, I appear to have overcome them by switching off my laptop screen when using a projector. So in my estimation my equipment has reached its usuable limits. If you removed the sharpening from your problem sequence and reported the results it could prove useful.

Regards Eric.

Not sure I saved an unsharpened version of that large panorama stitch, if I get around to it I may check that out.

Given that JRR had the same issues with the projector on his images, which were quite different from mine, I very much doubt that SX50 problem has anything to do with sharpening. And I never sharpen the sky, whatever else I sharpen (and the tearing/shimming issue we found wasn't specific to the sky, though of course bandng would be. But banding wasn't an issue with any of our tests.)

[LumenLux]

I'm just saying thank you to all for the personal experience info. And thank you John for the question. From the answers here, it is clear that the sharpening tools and methods are still changing and so are photographers preferences. We can't all be the first to know, and certainly can't personally try everything. This site continues to be great with the generous members.