When/How to Best Sharpen a Digital Photograph

[Colin Southern]

I often hear: "Sharpening really is the last thing to be done to any image, whether printing or uploading."

I lot of people still stick to this, but unfortunately it's far from "best practice" these days. Optimal sharpening usually requires at least 3 passes, at different parts of the workflow.

Capture sharpening is always done first to counter the effects of the camera's anti-aliasing filter and softness introduced during demosaicing, making the image much nicer to work on at high magnifications (Canon recommend 250 - 300%, 0.3 Radius, and varying thresholds depending on the ISO (thus noise) of the image (I normally use zero).

Content & creative sharpening are done mid-workflow - typically much lower amounts (40 - 120%, 2 to 5 pixel radius) to make things "pop".

Output sharpening depends on how big you're printing or displaying, thus it's pretty much the last thing done, but is best done on a copy of the image since it will need to be done if you're subsequently printing different sizes or displaying on a different medium.

The "industry standard" text on the topic was written by Bruce Fraser shortly before his death - "Real World Image Sharpening" http://www.amazon.com/World-Image-Sh...2402601&sr=8-2

Cheers,

Colin - pbase.com/cjsouthern

[Colin Southern]

Similarly, another common sharpening problem I hear is: "It was sharp as a tack before I downsized it."

Yes, that often happens. If possible use Bicubic (sharper) for the re-sampling, but at the end of the day, if you're cutting out a LOT of pixels then a LOT of them are going to be ones involving increased contrast around edges - and softness creaps in.

With agressive down-sampling it's ALWAYS necessary to resharpen to get things looking better, unfortunately.

Cheers,

Colin - pbase.com/cjsouthern

[The Blue Boy]

How cool is this site! Colin cheers for that.

Edit; It's worth adding I think that if it wasn't for this site, I would not have had a clue as to what Colin is going on about.

[Zephyrize]

I love this website as well!
I didn't pay any great attention to sharpening until I've read the "Understanding Sharpness" and "Guide to Image Sharpening" sections of this website.
But Colin, concerning the 'optimal' sharpening you explained, by doing it 3 times, do you mean actually: using 'unsharp mask' once (capture sharpening) / Save / 'unsharp mask' on the saved image (creative sharpening) / Save / 'unsharp mask' on the second saved image (output sharpening) ?

Isn't it making a lot of quality loss? Unless it's all processed losslessly under RAW?

And do you actually do batch sharpening processing for all images?

Maybe I'm missing something here.

[Colin Southern]

"But Colin, concerning the 'optimal' sharpening you explained, by doing it 3 times, do you mean actually: using 'unsharp mask' once (capture sharpening) / Save / 'unsharp mask' on the saved image (creative sharpening) / Save / 'unsharp mask' on the second saved image (output sharpening) ?"

Yes, although there's a bit more to it ...

When an image is processed by the RAW converter, a degree of unsharpness is introduced by the camera's anti-aliasing filter (personally I'd rather just deal with the aliasing), and the demosaic conversion where (using a 12mp camera as an example) the 3 million blue samples, 3 million red samples, and 6 million green samples are turned into 12 million pixels of all colours. Capture sharpening helps "correct" this - if you don't capture sharpen you won't notice any difference in a final print, but it makes it "less clear" to work on at large magnifications. People seem to have different tolerances for this - personally, I can't work on an image unless it's sharp (drives my eyes nuts) - so that's the first pass.

The 2nd has been called both content and creative sharpening - content because this can be where a lot of the hard work starts - often you'll have some areas that you want to sharpen, but others that you don't (possibly because you don't want to accentuate noise etc) - so this can involve lots of masking. And creative sharpening because that how you can make parts of the image "pop" - which may also need to be masked (or just use the history brush to roll back what you don't want a USM to be applied to). The settings for the 2nd pass vary a bit - a lot depending on the frequency of the image. A low frequency component (say a bunch of houses may well require setting that would turn a high-frequency component (say frizzy hair) crunchy or frosty - so it can take a fair bit of work to optimise things.

Output sharpening for printing or display is generally someting I don't get too hung up about - it's needs to be more agressive as images are printed or displayed smaller (but at their native resolution) - most of mine are printed 22" - 44", so I usually don't worry too much about it.

So - to answer the question - if you want to optimise each and every image than that's a lot of work - and almost certainly not worth it for a folder of holiday snaps. You can automate capture sharpening - and (to a degree) output sharpening - but content / creative sharpening is a toss up between something generic (and possibly quite acceptable) or something time-consuming and more detailed if the image warrants it. My shooting style (mostly landscape) involved shooting several dozen images - picking the best one - and the giving it lots of care and attention, whereas a wedding photographer may give extra special attention to one to be used as a wall-mounted portrait, but for the vast majority it's batch processing "one size fits all" all the way.

Does that help?

Cheers,

Colin - pbase.com/cjsouthern

[Daniel Salazar]

Hi Colin, thanks for the advice. Before reading this I never considered sharpening important. By default sharpening is set in Aperture, there is some degree of sharpening when importing the pictures and also some degree of general sharpening. I could increase or decrease both sharpening levels.

I tried once sharpening with the plugin from NIK, however the skin didn't looked nice, then I decided not to sharp. Now I think different about this subject.

The problem sometimes with sharpening is shown when having in a picture with objects that need sharpening and some others, like a person, that when having a lot of sharpening the skin looks really grainy. What should be then done?

What I've also done is to apply at the end, after output sharpening is applying again noise reduction, the first time I apply it is at the beginning.

Cheers,
Daniel

[Colin Southern]

Hi Daniel,

"thanks for the advice"

You're very welcome :)

"Before reading this I never considered sharpening important."

To be honest, I think that only about 1 in every 100 photographers really understands it - which is a pity. At a basic level I like to think of it as a kind of "super focusing" tool - I'll often hear of people saying "this lens is sharper than that lens" when proper sharpening would in most cases elevate the final image quality of a consumer lens over a poorly sharpened shot via a professional grade lens.

"I tried once sharpening with the plugin from NIK, however the skin didn't looked nice, then I decided not to sharp."

I've tried plugins, but to be honest, I found it easier to do it the way I've always done it. Different parts of an image may well require different sharpening - and skin is no different; in fact at times I even go the other way and apply slight blurring to skin to soften it. Ultimately, it's all about edge detection and contrast - and often with skin you don't want edges and contrast (at a texture level anyway).

"What I've also done is to apply at the end, after output sharpening is applying again noise reduction, the first time I apply it is at the beginning. "

Noise reduction and sharpening pretty much work against each other - as a rule, try to avoid sharpening noisy areas in the first place, but sometimes you can dodge a bullet with last minute noise reduction / dust & speckles filter / blur etc.

If you're a glutten for punishment, grab a copy of Bruce Frasers Real World Image Sharpening and a couple of asprin and start working your way through it!

Cheers,

Colin - pbase.com/cjsouthern

[Dave Humphries]

Hi Colin,

I'm learning from this too (thanks Sean for making a specific thread for it).

I haven't conciously been doing any capture sharpening, although having said that, I am aware that Adobe Camera Raw (I use 4.3.1) does apply some before I open the image in Elements 6.

I then sort out my levels and colours, then noise reduce with the Neat Image plugin (which I find brilliant), I might then apply brushed sharpening selectively before applying (usually two) USMs; one to improve local contrast and finally, one for the overall sharpen. I then save as (big) jpg.
If I want a smaller size pic, say to publish here, I undo the last overall sharpen, downsize the image, then USM again with settings more aggressive (as you suggest). But this last part is still being refined and obviously only works before I close the image.

I generally don't save the psd file because my pics aren't that good!

I use USM because it works for me, rather than 'sharpen image' or say, high pass variations - am I missing a trick with this workflow and/or only using USM?

Thanks,

[Colin Southern]

"I haven't conciously been doing any capture sharpening, although having said that, I am aware that Adobe Camera Raw (I use 4.3.1) does apply some before I open the image in Elements 6."

Applying capture sharpening with ACR would be ideal, but it needs to be done with an amount = 250 - 300, a radius of 0.3, and a threshold of 0 - 1 (for a low noise / ISO image) up to 6 or 7 for a high-ISO or noisy image (so as not to emphasize the noise), and I haven't been able to coax ACR into giving me these figures (as of CS3) so, regretably, I turn off sharpening in ACR. Be aware also that by default, ACR only applies sharpening to the PREVIEW image, not to the one that's opened up in PS (or PSE I assume) - you have to change the ACR options for sharpening to be carried through to the processed image.

Real easy test to see if an image is being capture sharpened - simply double-click the zoom control to zoom in to 100% - open up the unsharp mask control - dial in 300 / 0.3 / 0 and then toggle the preview off and on - when it's turned on you should see the image "snap into focus", making it much easier on the eyes to work on at high magnifications.

Cheers,

Colin - pbase.com/cjsouthern

[Dave Humphries]

Hi Colin,

I did/do have the ACR 4.3.1 sharpening turned on for 'All Images', not just 'Preview', but thanks for the warning.
However, my defaults* seem to be;
Amount = 25, on a scale of 0 to 150
Radius = 1.0, on a scale of 0.5 to 3.0
Detail = 25, on a scale of 0 to 100
Masking = 0, on a scale of 0 to 100

* by defaults, it seems to remember whatever was used last time, so lord knows who set these values, adobe or me

Now I am used to the USM in PSE6 which has 3 settings; Amount, Radius and Threshold, the latter I assume equates to Masking; it seems to work the same way, but what is 'Detail' in ACR doing? If Amount = 0 the Detail does nothing, even at 100.

So I spent a little time experimenting on an image and came up with some new defaults (well they work for my 6MP camera at 400ISO).

Amount = 70
Radius = 0.5
Detail = 100
Masking = 50
NR Luminance = 50
NR Colour = 50

The difference between Amount and Detail as I see it;
Amount = 100 with Detail = 50, or Amount 50 with Detail 100 look pretty similar at 100%, but at 300%, the former (higher 'Amount') produces more obvious 'jaggies' on diagonal white/black transitions than the latter (higher 'Detail').

I could ignore the detail tab in ACR and use your figures in PSE6 as capture sharpening settings, but a comparison between something saved as jpg in using each method produces a more pleasing effect from ACR, but admittedly, some of this is due to the NR I applied.

Hope that helps,

[Colin Southern]

Hi Dave,

The short answer to your questions is pop along to amazon.com and order a copy of Real World Camera RAW with Adobe CS3 by the late Bruce Fraser and Jeff Schewe - it answers your questions a lot better than I can - and is a real goldmine of information in these areas. If you're a little hesitant, buy the book and if you subsequently feel that it's not THE most useful and definitive text on RAW processing then I'll buy it from you for what you paid for it - and pay the freight!

The not so short (or easy) answer is that Detail is "similar in concept to USM's threshold, but totally different in application & function" (Unquote) ... at which point the book goes on to explain a lot more! TO be honest, I'm not an expert in ACR sharpening - because it doesn't allow me to use my familiar 300/0.3/0 USM settings I don't use it, prefering instead to do capture sharpening as my 2nd step of PP in photoshop proper (after dust bunny removal).

PS: The Capture Sharpening settings I outlined are only for RAW images, not for JPEGs being opened in ACR, as JPEGS require entirely different settings.

[Terry Tedor]

My apologies for reviving an old thread, but I think sharpening is probably one of the least understood topics in the digital darkroom, so maybe some others may get some use from this thread. I know I will.

Colin, please tell me if I'm understanding what you're saying regarding capture sharpening. You would prefer to do this in ACR, but since ACR doesn't offer the settings that you'd prefer, you're using USM in Photoshop itself, right? Basically, your workflow is RAW conversion with ACR, then to Photoshop, dust removal and then you use Photoshop's USM filter to do the capture sharpening. Make whatever other image adjustments you feel are needed and then do selective sharpening on areas that may need it. Resize for final output and apply USM again after resizing. Correct?

I've tried a few of the plugins and stand alone packages out there and haven't been too pleased with the results. Like Daniel said, I found their settings too harsh for skin tones and areas with fine detail. I've always been afraid of trying selective sharpening, as my masking skills are sorely lacking. Maybe it's time I work on that too.

Not to get sidetracked, but Dave mentioned the Neat Image plugin for noise removal. Does anyone know how it compares to Topaz's DeNoise? I made some comparisons between DeNoise, Nik's Dfine and Noise Ninja; IMHO DeNoise runs circles around both and am curious how it might fare against Neat Image.

I'm using CS4 and ACR 5.6 and confirmed that the range/defaults that Dave reported above hold true in ACR 5.6. I was just working on some full size files 50D converted RAW files yesterday and went back and tried USM with your recommended settings and must say there is quite an improvement in the full size files using your settings. Now I'm going to have to try the sharpen, edit, resize, sharpen again route and see what happens then.

I just realized I already have Bruce Fraser's "Real World Camera Raw with Adobe Photoshop CS4". I had ordered it over the holidays along with some other Photoshop related titles that I placed ahead of it on my reading list. Looks like it may have to make a temporary leap to the top of the list.

Thanks again!

Regards,

Terry

[Colin Southern]

Colin, please tell me if I'm understanding what you're saying regarding capture sharpening. You would prefer to do this in ACR, but since ACR doesn't offer the settings that you'd prefer, you're using USM in Photoshop itself, right? Basically, your workflow is RAW conversion with ACR, then to Photoshop, dust removal and then you use Photoshop's USM filter to do the capture sharpening. Make whatever other image adjustments you feel are needed and then do selective sharpening on areas that may need it. Resize for final output and apply USM again after resizing. Correct?

Yes. (that was easy )

my masking skills are sorely lacking. Maybe it's time I work on that too.

Making selections and painting layer masks are probably two of the things I do most often in Photoshop. Considering that you can paint masks with an opacity of less than 100%, and vary the opacity of the entire mask afterwards, you have a tool that's INCREDIBLY powerful. Ironically this powerful tool is often misunderstood and yet it's actually very easy to understand (might be a good topic for another thread?).

Not to get sidetracked, but Dave mentioned the Neat Image plugin for noise removal. Does anyone know how it compares to Topaz's DeNoise? I made some comparisons between DeNoise, Nik's Dfine and Noise Ninja; IMHO DeNoise runs circles around both and am curious how it might fare against Neat Image.

All great programs I'm sure, but it does beg the question of why they seem to be needed by people so often - I have to admit that I do wonder if perhaps some folks aren't nailing their exposures correctly.

I just realized I already have Bruce Fraser's "Real World Camera Raw with Adobe Photoshop CS4". I had ordered it over the holidays along with some other Photoshop related titles that I placed ahead of it on my reading list. Looks like it may have to make a temporary leap to the top of the list.

You might like to add Real World Image Sharpening 2nd edition and Real World Color Management to the list as well - I think you'd find them invaluable in the areas your talking about.

With regards to sharpening (or blurring) for skin - it's a whole new ball game - best discussed in another thread if anyone is interested.

Hope this helps

[Terry Tedor]

Ironically this powerful tool is often misunderstood and yet it's actually very easy to understand (might be a good topic for another thread?).

I guess that's why I've probably never taken the time to learn how to do it. I know it is a powerful tool, but I've never been very clear on the basics of how to do it, when and why. Yes, maybe another thread is called for.

You might like to add Real World Image Sharpening 2nd edition and Real World Color Management to the list as well - I think you'd find them invaluable in the areas your talking about.

Those were added to my wish list at Barnes & Noble.com yesterday. I hold Mr. Fraser in very esteem. His passing was a great loss.

With regards to sharpening (or blurring) for skin - it's a whole new ball game - best discussed in another thread if anyone is interested. Hope this helps

Sure, why not! We'll keep you busy!

[Colin Southern]

I guess that's why I've probably never taken the time to learn how to do it. I know it is a powerful tool, but I've never been very clear on the basics of how to do it, when and why. Yes, maybe another thread is called for.



Those were added to my wish list at Barnes & Noble.com yesterday. I hold Mr. Fraser in very [high?] esteem. His passing was a great loss.



Sure, why not! We'll keep you busy!

Oh well - you start the threads, and I'll throw my 10c worth in

[pwnage101]

Hmm usually it's 2c but i guess 10c is five times better

Anyway, I'm confused about sharpening when downsizing. I assume creative sharpening is done before the resize, then output sharpening after?

If I understand correctly, it should definitively be:
-250-300%/0.3px/V,
-40-120/2-5/V,
-resize,
-V/V/V
(Amount/Radius/Masking respectively, and V for variable)

As a note, I'm working with 10 megapixels.

Between which steps would you place Local Contrast Enhancement ?

[Terry Tedor]

Oh well - you start the threads, and I'll throw my 10c worth in

I'll take oyu up on that! It may take me a few days to formulate some intelligent questions though.

[The Blue Boy]

Just gonna give this thread a quick bump....

Colin refers to the book Bruce Frasers Real World Image Sharpening. It really is a must read. It isn't all about the sharpening either. It contains some of the best tips I've read in a book for ages. It's great for noise removal, masks and selections.

Buy a copy people!

[Dave Humphries]

Anyway, I'm confused about sharpening when downsizing. I assume creative sharpening is done before the resize, then output sharpening after?

If I understand correctly, it should definitively be:
-250-300%/0.3px/V,
-40-120/2-5/V,
-resize,
-V/V/V
(Amount/Radius/Masking respectively, and V for variable)

As a note, I'm working with 10 megapixels.

Between which steps would you place Local Contrast Enhancement ?

Hi Troy,

I pretty much agree with all your numbers and to answer the last question, I would put it between Capture and Content/Creative (1st and 2nd). I wonder what the book says.

Cheers,

[The Blue Boy]

@Dave

"I wonder what the book says"

Buy a copy!

:-))))