#4 Sharpening


Sharpening...

...in digital image processing jargon, sharpening is about increasing edge contrast and has nothing to do with focus. .  ---http://luminous-landscape.com/tutorials/instant_photoshop.shtml

This picture below captured from digital video shot at the Beijing Opera in Beijing, China.

Because it is a video capture, the resolution is only 720 x 480 pixels. There is a lot of detail in the picture, especially in the headdress and the eyes of the subject... to improve the detail in the headdress I sharpened the picture, using a function called convolving.

Convolve allows you to mathematically manipulate the data, that is the pixel value of each pixel in the picture. This is accomplished by using a matrix grid that overlays the picture. The under lying pixels are then processed or enhanced.

To sharpen a picture you use a convolution matrix with the unlikely name of Unsharp Mask

If you over do Unsharp Masking you'll start to see white fringing around parts of the image... so use this function sparingly and avoid the white fringing. If your software allows you to use LAB Mode (not available in PhotoShop Elements), sharpen in the luminance or lightness layer...

Interestingly enough, today's digital cameras do this unsharp masking in the camera when you save the picture in Tiff or Jpg format.... Some cameras even allow you to set the level of sharpening. But, if you save your picture data in RAW format, no image processing takes place at all and you must do the sharpening later in the computer with your image processing software.
Always do sharpening last just before you print the picture.



 UnsharpMask Dialogue
Roll mouse arrow over picture to see the effect
 If you check preview, you can see how the different values affects the entire photo ---on the canvas. Clicking in the sharpening window in the above Filter Dialogue box shows you the before/after affects of the filter .



Using Filter > Unsharp Mask
Here are Some Sharpening  Recipes for you to try when sharpening a photograph for publication. The numbers are for the Filter ---> Unsharp Mask.  The given values below are conservative -- a good place to start...
Basic Sharpening
Soft Subjects
Portraits
Set
Amount to 125%
Radius to 1
Threshold to 3 		Sharpened red flower
 Set
Amount to 150%
Radius to 1
Threshold to 10 		Soft Image Racoon fur Set
Amount to 75%
Radius to 2
Threshold to 3 		Sue
Moderate Sharpening
Maximum
 (for slightly out of focus pictures)
 All Purpose
Set
Amount to 225%
Radius to 0.5
Threshold to 0		 Sunflower moderate sharpening
 Set
Amount to 65%
Radius to 4
Threshold to 3		 Scanned out of focus slightly
 Set
Amount to 85%
Radius to 1
Threshold to 4		 REd brick building
WEB Sharpening
Mid Tone Detail !!!
...Clarity...

Click on slideshow to view larger version
Set
Amount to 400%
Radius to 0.3
Threshold to 0		 Sharpened for web
 Set
Amount to 20%
High Pixel Radius 78
Threshold 0		 Carving in Mexico

Mega Ultra Professional Sharpening

using L - A - B (Photoshop Only)


Step1. Duplicate your Photo (PC)(Control + J)

Step 2. Convert from RGB to LAB using the Image/mode menu

Step 3. In the layers palette open Channels
and highlight only the Lightness Channel 
 Channels-LAB lightness selection
Step 4.  Choose Filter/Sharpen/unsharp mask or Smart Sharpen
we will only be applying sharpening to the Lightness channel.

When sharpening always keep the filter window at 100%
A radius > (greater than) 3 belongs to the realm of special effects, but none the less --experiment!

A rule for figuring the radius setting is to divide
 the resolution of the file in pixels per inch (ppi) by 200
So if you photo is at 300 ppi the radius is = 300/200 = 1.5

Clicking with the pointer (hand) in the result window will reveal what the picture looked like before you changed the radius settings

Step 5. Click okay
Step 6. Duplicate the layer you just sharpened
Step 7. Apply the sharpening filter again, but this time increase the sharpening for areas that can hold more sharpening, stay away from edges, (do wall textures, animal skins, landscapes) Do not worry if other parts of the photo are starting to look ugly (we'll mask the effect)

Step 8. Click okay
Step 9. Go to the layers palette and hold down the Alt Key and click on the layer mask Icon
This puts a black mask over the ultra sharp layer and blocks the extra sharpening

Step 9. Set the foreground color to white

Step 10. Select a soft edged brush and paint over the areas that can use the mega-ultra professional sharpening... you can lower the opacity of the brush to limit the effect or increase the effect by painting a second time over the mask.

Step 11. you can see the mask if you hold down the alt key and click on the mask
 Black Layer Mask
Step 12. To get back to mask painting click on the colored layer thumbnail in the layers palette and then click the black mask beside it...

Step 13. ...Continue until well sharpened... and you are ready to print...