Out-of-Focus Blur Tutorial
Shifting the Focus
Well, things do go wrong from time to time. Here the camera focused on the background rather than the foreground. Normally this photo would be destined for the bin, but it can be rescued. First of all, to determine the type and magnitude of the blur, we’ll zoom in and examine the shiny bits (point sources) in the image.
This is a highly magnified part of the mans eye, and has a diameter of 13 pixels (counted vertically). When counting the diameter, count the actual number of pixels and subtract one. This is for the same reason why one is subtracted for motion blur as explained here. The point source in this case may not be that clear, the the following two definitely are.
They are below the ladies ear on the left, and have a diameter of 13 or 14 depending on whether you count horizontally or vertically. Their diameter is a little less than that of the eyes because they are a little further away and hence a little more in focus. Any setting between 13 and 15 is OK for Focus Magic’s “Blur Width” setting for this image.
It is important in this case to make a selection of only the area to focus using the lasso tool so that the areas that are already in focus are not processed by Focus Magic.
After selecting Focus Magic from the Filter menu (for Photoshop) the diameter of 15 is entered in for the Blur Width, to produce the following.
Notice how the red light is unaltered because it is outside the selection. See how the circle of light from the “glint” in his eye has become a brighter and smaller circle of light, as it should do.
Where the ladies ear-ring was not visible before, it can now be seen clearly.
After focusing the whole image you get:-
Then just for fun we can make the background out of focus by first inverting the selection to be as follows:-
Now that the background is selected we can blur it using Gaussian Blur (which, by the way, is not the same as out-of-focus blur) with a radius of 5 and then deselect, to produce the following:-