Why all Digital images need SHARPENING

[ricktas]

I thought it would be good to explain why ALL digital images need to undergo some sharpening.

A digital camera sensor is made up of millions of tiny lenses, each one captures one colour and a brightness level. Then through an amazing process, this analogue light capture is turned into the digital colour image we see on our LCD's and Computer screens.

Below is an image of a sensor, sitting on a Bayer pattern filter, one of a few methods used to capture our images, but probably the most common.



Now each pixel site is a small (we are talking microns) width, and they laid out side by side, checker board style on the image sensor. Like this:


(image courtesy IBM, taken with an electron microscope of an actual image sensor)

Notice how each pixel site is separated by that small area (the tan part in the image above), well that is the reason why ALL digital images need sharpening. Your images when captured have a small area between each pixel site on the sensor where no light is captured (we are talking really small), but that 'dead' area, means that all digital images are not as sharp as they could be straight out of the camera. The technology inside your camera fills in this 'dead' area by alligning the data from each pixel up against the data from the neighbouring pixels, it is clever, but the result is your digital images straight from your camera will always be a little soft.

So sharpening your digital images is an important part of your workflow.

There are various methods of sharpening available, most commonly used would be USM (Un-Sharp Mask) a term carried over from film and dark room processing. It is worth investigating other sharpening methods (and there are a few).

I hope this has helped members understand why they need to sharpen their digital images.

I am leaving this thread open as members can discuss the various methods they employ to sharpen their images, and other members can learn of maybe better ways to do it.

[ricktas]

I never use USM.

My personal way of sharpening, i used to do step-by step, (before i knew how to create actions).

But now the wonderful people at Action Central have basically made an action that does what i was doing (actually a bit better than i was achieving).

I use Dave's Sharpening Actions - in particular the High Pass Sharpening, from www.atncentral.com

[hoffy]

What is the difference/benifit of using this action as opposed to USM?

[ricktas]

High Pass sharpening has two big advantages. The first advantage is that the sharpening is done on a separate layer. With High Pass sharpening applied on a separate layer, not only can the sharpening be adjusted at a later date but also can be completely undone simply by deleting the layer that was added during the High Pass Sharpening process.

The second advantage is that the High Pass sharpening technique uses the High Pass filter, which isolates the edges. Thus, High Pass sharpening applies sharpening primarily to the edges where it is needed and protects smoother areas from the sharpening.

[ricktas]

this is how you can do High Pass Sharpening manually.

On the Layer palette select your Background Layer and right click. Select Duplicate Layer.

With this new layer highlighted select Filter / Other / High Pass. Set the Radius to 10 and click OK.
Zoom into your image to Actual Pixels level so you can better see what you're going to do next.
Go back to the Layer Palette and select Hard Light (you can also select soft light for a variation) from the left drop down.
Now go to the Opacity Slider and select a level of sharpening that seems best to you. Usually something between 20% and 70% will be best.

[hoffy]

OK, thanks! Looks like I had part of it right!. My action was to create a separate layer & apply USM to that (really go over the top with it). I would then reduce the opacity of the USM layer to what looks acceptable.

I will try the High pass method. Sounds interesting

[Kevin M]

High Pass sharpening has two big advantages. The first advantage is that the sharpening is done on a separate layer. With High Pass sharpening applied on a separate layer, not only can the sharpening be adjusted at a later date but also can be completely undone simply by deleting the layer that was added during the High Pass Sharpening process.

The second advantage is that the High Pass sharpening technique uses the High Pass filter, which isolates the edges. Thus, High Pass sharpening applies sharpening primarily to the edges where it is needed and protects smoother areas from the sharpening.

Thanks (yet again) Rick for reminding me about this ...completely forgotten about this I will have to bookmark this for latter reference.

[Paul G]

I use Dave's Sharpening Actions - in particular the High Pass Sharpening, from www.atncentral.com

Rick I just had a look at this. How do you use/open/apply it as it is a zipped .atn file-type?

[Kym]

Rick I just had a look at this. How do you use/open/apply it as it is a zipped .atn file-type?

Unzip the ATN file and put it into a folder (My Documents - whatever)
Open the Actions Palette inside Photoshop - F9 key or go to Window>Show Actions

Look at the upper right hand corner of the palette there is a small arrow.
Click this to open the Actions Menu.
Click ‘Load Actions’, find your ATN file
All cool!

ATN files work on both PC and Mac

Edit: Cross posted

[Paul G]

Thanks guys I'll give that a go

[Paul G]

OK I've got the Action in place but it won't work.
I am trying to do it on a duplicate layer following these instructions from the Action Central website but I get no result?

How to run an action and interact with it.
In the Actions Palette (or "Panel", as it's known in CS4), click on the action set you wish to run. Click on the arrow next to the set and you'll see one or more actions within the set. Click on the action you wish to run, and the steps in the action will be performed. Often you'll see a screen that offers you the option to continue or stop. If you press stop, you'll be dropped out of the action and nothing further will happen. If you press continue, you'll be offered an instruction and some sort of interaction to perform on your image, after which the action will resume or end. Finally, many actions operate on layers. This means that you can adjust the effect after the action is completed by changing the opacity or even the blend mode. This makes actions very powerful interactive tools.

[katiedransfield]

I use Dave's Sharpening Actions - in particular the High Pass Sharpening, from www.atncentral.com

I tried it, and agree it's great. Definitely better results than I was getting in a lot less time. Definitely worth a go.

[David]

Thanks for the more than useful tips guys: AP is an education in photography.

[clm738]

Hi Guys,
I am trying to do raw processing in CS3 and I am having trouble working out the best way to sharpen my photos.
Could you please help me out here as to the best method for sharpening.
Thanks

[lindenneill]

Well i think we need to know what level of knowledge you have with cs3 before we answer. Then we will know how in depth we have to go with instructions.

There are a few different methods and most should have tutorials online if you do a google search. Each one seems to suit certain types of photos and sometimes ill try a couple of them on different layers so that i can directly compare the effect they are giving.

The main methods I use are

Smart Sharpen under the sharpen tab in photoshop
High pass filter under "Other" in the filter tabe in photoshop

Sometimes even a combination of both. They both give a different effect to the image.
Both of these methods should have tutorials online to follow. Below is a website with alot of helpful tutorials. Ive linked the one related to sharpening.

http://www.ronbigelow.com/articles/s...1/sharpen1.htm

[lindenneill]

The link above is focused on the unsharp mask filter in photoshop.

Below is a good tutorial on high pass filter. Where it says to use overlay blending method i prefer to use the soft light option

http://www.photoshopessentials.com/p...pen-high-pass/

All of these methods are done outside of camera raw as well. I dont like adding sharpening to the raw conversion process. Mose people reccomend that its done as the last step in the editing process because of the noise it adds to the image.

[N*A*M]

LAB mode gives me the cleanest results, regardless of sharpening algorithm

[Kym]

Mod note: Thread merged.

Refer NTP: http://www.ausphotography.net.au/for...ss_photographs

[lindenneill]

Nam do you apply sharpening to the whole image or just the lightness channel when in LAB mode.?

[ricktas]

Hi Guys,
I am trying to do raw processing in CS3 and I am having trouble working out the best way to sharpen my photos.
Could you please help me out here as to the best method for sharpening.
Thanks

Do NOT sharpen your RAW files. Sharpening should be the last thing in your workflow, before saving the file. Convert your RAW file into TIF/PSD etc, work on it in photoshop, do all your other adjustments, and only then Sharpen.