Sharpening - A brief introduction

Thanks for reviving Cam, I had forgotten we had this.

Here's also a link to a nice article on why sharpening is recommended after downsizing. Cambridge in Colour, Image resizing for the web and email.

This shot was sharpened for the web using USM in Paintshop Photo Pro.



Edited by brettania - 01 May 2012 at 01:47

Great idea Cameron. Here's my contribution:

1: Downsized in Lightroom and exported without sharpening:


2: Downsized in Lightroom and sharpened for screen (standard)


3: same as 2 but added USM 200%, radius 0.2, treshold 1 pixel


4: same as 2 but added PhotoKit sharpener for web 1024 superfine edge sharpen with 60% layer strength


Shot with a Nex 5 + kit 18-55
Also note the file sizes:
1: 231 kb, 2: 251 kb, 3: 264 kb, 4: 270 kb

Let me add this short addendum here which is from a recent discussion about improved noise performance in newer cameras compared to A900/850.
Though the noise might be of a finer grain especially with A99, to be honest I wouldn't want to directly write off the first generation FF Alphas. IMO with the correct settings applied to the RAW files of A900/850 quite similar performance can be achieved.


Capture sharpening - know your RAW converter
"Sharpening Masking" and "High ISO shot noise reduction" via CameraRaw

Mind you, nowadays you not only need to know your camera, but also have to get familiar with your used RAW converter

In the detail tab of CameraRaw (ACR/LR) there are the following control sliders available which are quite helpful in masking the applied capture sharpening as well as give control to high ISO shot noise reduction.

Sharpening:

• Amount - intensity of edge contrast
  
• Radius - size/thickness of sharpened edge
  
• Detail - adjusts how much high-frequency information is sharpened in the image and how much the sharpening process emphasizes edges
  
• Masking - edge mask control; "0": everything in the image is sharpened, "100": only the strongest edges are sharpened while other uniform areas are masked out

Noise Reduction:

• Luminance - reduces luminance noise
  
• Luminance Detail - luminance noise threshold (higher values preserve more detail but can produce noisier results; lower values produce cleaner results but also remove some detail)
  
• Luminance Contrast - adjust smoothness (low values) / blotchiness (high values)
  
• Color - reduces chroma noise
  
• Color Detail - chroma noise threshold (higher values protect thin detailed color edges; lower values remove color speckles)

In CameraRaw there is also a neat feature available in the sharpening tab to immediately give a rough preview of the sharpening effect applied respectively the areas masked out !!!
Same as the well known method in CameraRaw to directly see clipping by holding down the "Alt" key ("Option" key on a Mac) while adjusting the sliders for "Exposure" or "Recovery" for the highlights, respectively "Black" slider for the shadows (same way like used in "Levels" command in PS while adjusting white and black points).

Hence, if you hold down the "ALT"(Win) / "Option"(Mac) key and move at the same time the slider for Masking (or Detail), the image in CameraRaw will turn into a b&w image, too and you will directly see the mask/contours used for sharpening. In principle this is the same like applying some kind of highpass or edge sharpening technique where flat sections are excluded and only high contrast areas are emphasized.
Or in short: Masking slider is used to find and emphasize the contours by an edge mask and this edge mask can be made visible via the "Alt"/"Option" key, while Detail slider somehow controls the edges/sharpening halos.


Try the following ACR settings on an A900/850/*insert your camera here* high ISO shot:

Noise Reduction:

• Luminance = in the range of 25-30
  
• Luminance Detail = 15
  
• Luminance Contrast = 15
  
• Color = 65
  
• Color Details = 50

Furthermore set in the Sharpening section the sliders:

• Detail = ~50

and especially most important

• Masking (hold down ALT/Option key and move the sliders to mask areas and only emphasise contours) = values between 55-80

Happy shooting!

See also this link: Sharpening and noise reduction in Camera Raw

Thank you to all contributors to this most useful thread. I deeply appreciate the enormous amount of vital information which is included. I am certain that it will be enormously helpful to my photographic efforts.

Respectfully and gratefully,

JL

Bart VanderWolf at LuLa has a system for optimum sharpening using USM. It is a great system for those that use USM - no more guessing about what values to use for a given shot. He has a thread explaining it there. (A little cross pollination is good. I try to give them reasons to visit here too )

Link Added
http://www.luminous-landscape.com/forum/index.php?topic=68089.0

Edited by FineArt - 17 February 2013 at 20:09

Hi,

Excellent article, very helpful indeed.

Cheers

Vindy