Determine the Type of Blur
Nearly all blurred images have either:-
A) Out-of-Focus Blur
- Each pixel becomes a circle of pixels
- The blur is the same in all directions
B) Motion Blur (also called Camera Shake)
- Each pixel becomes a line of pixels (or a streak) in a certain direction
- The blur is only in one direction (and edges parallel to the blur direction remain sharp)
The first thing to look for is shiny objects which either become circles of light or streaks of light.
Here are some examples of each:-
Examples for "Out-of-Focus" Blur
In this photo you can see how the glint in the woman’s eyes and earrings have become circles of light, and that the blur is the same in all directions.
This medicine bottle in the background of a photo has light reflecting off it. This is a point source which has become a circle when it became out of focus. The image on the right has zoomed into that point source, and shows that the diameter is about 18 pixels (the distance between the black dots).
Note that we have placed the black dots approximately in the middle of the blurred edges.
This image of some trees in the background of a photo has a feint point source (pointed to by the arrow).
Sometimes you can have a point source bonanza as shown here. Here we have two photos, one taken out of focus and one taken shortly afterwards in focus. They clearly show the “circle effect” for point sources.
Here is another difficult one. There are two point sources in this blurred picture of a car’s license plate. The diameter of the point sources determine the Blur Width setting to use in Focus Magic (see Tutorials).
This is an example of a “zoomed in” photo which – interestingly enough – would normally be considered to be “in focus”!
It does however have a point source with a diameter of a few pixels and can therefore be sharpened a little bit. Nearly all photos can do with sharpening with a Blur Width of around 1 to 3. Some Focus Magic users sharpen all their photos with a standard Blur Width of 2.
Examples for Motion Blur
In this photo of a tiara there is clear motion blur (vertical streaks).
In this old photo of a bicycle in front of a car, you can see many point sources (as indicated by arrows) which have become blurred at about 45 degrees. They look to be a bit like double exposures. This is because the camera went “slow – fast – slow” with more light being captured at the beginning and end.
When this photo was taken the camera was moving at about 45 degrees.
When point sources are hard to find, looking at edges may be the best way to find the blur direction. In this case the edge of one spoke is perfectly in focus. Also, the rim of the wheel is perfectly in focus in about the same direction. It is true that the opposite side of the rim isn’t quite as well in focus, but the blur direction is validated from other parts of the image.
In this photo of an old wooden tennis racket, the two yellow arrows show edges that are in focus, while the light blue arrows show edges that become wider and also more blurred. The sharp edges show the direction of the blur.