Sharpen ALL Digital Photos?

[cmcadams]

I am an amateur and I've been using photoshop for about a year. I read somewhere recently that ALL digital photos need sharpening. Is this true? I will say that I have been a bit underwhelmed at the clarity of some of my photos, even when I use a tripod. So what is the consensus, do all digital photos need some sharpening? (Unsharpen mask, etc.)

Thanks in advance!!

[ohenry]

Yes, digital files require some sharpening, either in the camera or in post processing. Even with the best lenses and cameras, the nature of pixels requires contrast sharpening. (This isn't a focus issue, it's the nature of the beast)

[Gary Mayo]

Many people use something unsharp mask. It is a step in PP for all my photos.

[oldugly]

If you are using Photoshop CS3, and shooting RAW, there is a great sharpening tool in the RAW processor. Click on the detail icon, set the zoom at 100%, hold down the ALT key and you can see your adjustments in black and white. Sure makes it a lot easier.

[jfrancho]

If you are using a DSLR, probably. If using a DSLR and shooting in raw format, definitely. Point and shoots - depends on the model. I sharpen images from my Canon DSLR using The Light's Right scripts (all of Mitch's scripts and actions are GREAT!) - see the stickies for links details, I have quite a few tutorials that detail how to use them. Images from little Canon S500 are fine straight out of the cam. I can get perfectly sharp images straight out of my SLR, but that requires some special circumstances and parameter set. I also get by fine with conservative sharpening of raw files converted in DPP.

[ohenry]

Originally Posted by jfrancho

Images from little Canon S500 are fine straight out of the cam. I can get perfectly sharp images straight out of my SLR, but that requires some special circumstances and parameter set. I also get by fine with conservative sharpening of raw files converted in DPP.

Yes, but in these cases the camera is adding sharpening based on your parameter set. Bottom line is that either the camera or post processing needs to add some sharpening -- the degree of which depends on the strength of the anti-aliasing filter on the sensor.

[jfrancho]

That was my point, read the whole post to expose the context

[peterst6906]

I hope the following is useful and it attempts to explain why sharpening is required, whether that sharpening is done in camera or in post:

In the conversion of an analog signal (eg. captured directy on a sensor or scanned film) to a digital signal there are limits to how much detail the sensor can resolve. Unfortunately, signals with a higher frequency than the resolving power of the sensor can lead to moire, banding, popping, etc. all of which are not desirable in a photo (if you search for Nyquist-Shannon sampling theorem you'll be able to research the reasons, but I can explain it in a separate post if you like).

As a result, most sensors are covered by a low-pass filter designed to prevent the passage of signal with a higer frequency than the sensors resolving power (to reduce the risk of these flaws appearing).

The low-pass filter is also called a blur filter or anti-aliasing filter and its nett effect is to reduce the sharpness of the image slightly.

Additionaly, when the RAW data is converted into an image (whether in camera for a jpeg or a software package), the demosaicing process that constructs RGB values from the individual R, G and B photosensors in the array (for a Bayer pattern sensor) results in a small amout of additional blurring of the image.

As a result, all images that are produced through an analog to digital conversion require sharpening.

How you go about doing that ansd what type of workflow you use is something totally different and very much an individual choice, although many people are moving to a three-stage sharpening workflow since the publication of the late Bruce Fraser's book on sharpening at the end of 2006.

I see mentioned about the use of the sharpening tools now in ACR. They are good, but there are two points to note:

1. they are designed to be used as part of the Bruce Fraser approach to sharpening (he was heavily involved in the development of the tools both for PS and Lightroom); and
2. as a result, they are designed only for the capture sharpening, not for creative or output sharpening.

As John mentioned, Glenn Mitchell has developed a set of scripts that are an open source application of the Fraser sharpening approach and it works similar to the Photokit Sharpener available from Pixel Genius.

In Lightroom now (with LR2.0 beta), the full Fraser workflow is being implemented and the alpha version is expected to have additional controls that are not in the beta (eg. creative sharpening and further enhanced output sharpening). Since the RAW conversion engine in LR and ACR are the same, it's probable that the same tools will appear in ACR towards the end of the year (possibly with the release of CS4 rumoured to be in October).

The alternative is to perform a single pass of sharpening at the end of the workflow at final size and resolution that is designed specifically for the output medium (Fraser's workflow also stresses this point).

Regards,

Peter

[cmcadams]

I appreciate the responses. I have a follow-up question. IF all digital photos need some sharpening (I'm using a Nikon D80), then what about portrait or other photographs that I may use the reduce noise filter or blur to make skin smoother or blur the background. In essence, if I sharpen just to turn around and "unsharpen" won't the photograph begin to look overprocessed and less natural?
Hence, is there a specific order I should follow to the sharpening and bluring of a photograph?

Thanks!

[Mr. Pickles]

Originally Posted by cmcadams

IF all digital photos need some sharpening....

You missed a point by making the statement above. Depending on settings in the camera or default ones in your software, SOME images may NOT need extra sharpening, and JPG's are more than likely the ones that will not.

As for Noise reduction, most will say that you should do that step BEFORE sharpening. But some (probably a small percentage), while doing post processing, do a couple of sharpening steps. Either way, the last sharpening you do is designed to sharpen the edges or "things", and if there is noise, the edges of that noise are "sharpened" as well if it is still there.

[peterst6906]

As Pickles said, if you are shooting with in camera jpegs and have in camera sharpening settings turned on, then you may not have to do any additional sharpening. You are giving control of the RAW conversion and sharpening over to the firmware engineers from the manufacturer and they know what they are doing, so the results are often excellent out of camera.

However if you are shooting RAW or you intend to do additional processing of a jpeg, sharpening as part of your post processing routine will always produce a better result.

In relation to sharpening and noise reduction, the normal approach as mentioned by Pickles is to apply noise reduction before sharpening. This avoids exactly what you mention so that you don't sharpen detail and then desharpen it during noise reduction; and also so that you don't sharpen the noise and create problems for yourself later in the workflow.

Also, if you do it correctly, you can do it the other way around since sharpening and noise reduction are really opposites of the same concept. Sharpening attempts to increase the apparent sharpness of an image by increasing the contrast on either side of an edge so that the edge stands out more and is more noticeable to the eye. Noise reduction aims to reduce contrast in the non-edge or surface areas. Often the edge mask that you might build to sharpen through can also be used for noise reduction by inversing it. That way you can sharpen the edges and reduce the noise elsewhere.

In either case, whether you perform noise reduction first or second (first is my approach before any sharpening when I need to use it) you still should really be aiming to sharpen edges and reduce noise in other areas, so they don't necessarily have to overlap too much unless you just sharpen or blur globally without using a mask.

If you are applying some creative blur to your image, then there is no reason why this should affect your sharpening where it is needed. Creative blur is usually brushed into areas that are not the main subject, so if you blur away sharpening in those areas it doesn't matter, since the purpose of applying the blur (eg. even to skin in portraits) is to reduce detail and help lead the eye to other parts of the image that are sharp.

Again, in this situation the image shouldn't look over-processed unless you apply too much blur, because the areas that you blur are different from the areas where you want the sharpening (eg. in a portrait you might apply some blur to the skin, but sharpen the eyes, lips and hair. The blur and the sharpening are in separate locations of the image and don't affect each other).

Regards,

Peter

[cmcadams]

Thanks everyone!