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Gaussian Blur ?
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I’ve noticed alot of people mentioning the use of gaussian blur to improve DOF, reducing a distraction etc…
What are your opinions on this ? Personally, I see this as too much manipulation and would never use it.
I’d prefer to go back and retake the shot and get my technique right instead of ‘fixing’ it
afterwards.So what do you think ;) ?
Mark
I think it’s a valid tool to use, provided it’s used correctly and sparingly. However, if it’s limited DOF you want to obtain, you may be better off using the lens blur filter, as it’s difficult to get a realistic effect using gaussian blur.
Having said that, I completely agree with the idea of getting it right in camera in the first place and would always endeavour to do so myself, if only to save myself the time and effort of having to do it later. However, this is an example where it may not be possible to get it the way you want it in camera, for a number of different technical reasons (e.g., slow max. aperture, too much available light, or small sensor or more likely a combination of these).
As I have said in the other forum you have the know how and can use it without it showing up, then fire away.
There is a difference between ‘Gaussian Blur’ and ‘Lens Blur’.
Real ‘Lens Blur’ is caused by the curvature of the leaves of the aperture. You get slight multiple exposures when something is outside your depth of field. Thorsten is right, to give the effect of being out of focus due to limited depth of field you should only use ‘Lens Blur’ – Filter>Blur>Lens Blur…
Once there you have a good level of control, see below:
One of the times I find Gaussian Blur handy is if I have to scan a paper photograph and reproduce it in a larger size.
This is what I do. (It also can have a nice effect on a portrait without giving that plastic skin look)Load the file on Photoshop. Duplicate layer. apply 20 pix Gaussian Blur. Change blending to lighten. Reduce opacity to
approx 50%. Now duplicate the layer again. Change blending to darken and reduce opacity your liking.I’d personally never dream of using Gaussian Blur to give the effect of a shallow DOF, but then again I nearly always shoot at f2.8 and below so it’s rare I’d have to. But that said, I don’t think it’s cheating if you can get away with it. As per Thorstens suggestion (nice to see the name change!!) I’d be inclined to use Lens Blur more so than Gaussian Blur if I was to go down this route. Personally the only time I use Gaussian blur is if I’m brushing in or out detail in masks – I’ll use the blur to remove the hard edges on the masks.
I often use Gaussian Blur when processing my images… not necessarily to compensate for depth of field but more for viewer control.
By “viewer control” I mean being able to force someone that is looking at my images to go straight to the portion of the image that i want them to be drawn to. as humans when we look at photos of other people or animals we are always drawn to their eyes first and foremost. another tid bit is that we will also be automatically drawn to what is in focus first as well…
so like in the image below i wanted to eccenuate the eyes of this lion and then draw the viewer in towards the teeth. so how i did that was thru Gaussian Blur.
I first take the original image, make all of the necessary tweaks and adjustments then in the final steps (on a lowres image ex 600x400px) i would duplicate the original layer and name it BLUR set it above the original in the layer order. Then I apply a Gaussian Blur to the BLUR layer and I’ll use a value of like 3.0 (keep in mind this is a lowres image, larger value for hi res files is needed). once the blur is added i then adjust the OPACITY of the BLUR layer to about 30-35% giving a nice soft glow since the semi transparent blurred layered sits over the opaque crisp original.
now comes the part where i gain control of the viewer… I then add a layer mask to the BLUR layer and set my paint brush to be about 50-60% opacity (you may like more or less) and then go thru and mask out (or paint over) the areas that i want the viewer to be drawn to. in this case it is the eyes, teeth & snout. by masking out the BLUR layer, the layer below shows through more clearly and seems to me more in focus than the surroundings.
the shot was originally at f2.8 already so there was a shallow depth of field but i want a bit more of a dramatic look to the image. there are many instances where this technique can be used… i use this method alot in many different arenas such as portrait, glamour, sports, concerts & wedding photography. in portrait/glamour it is very helpfully since the use of Gaussian Blur and easily hide imperfections in the skin and make images more appealing to the eye… well in my eye anyways. hehee.
I’d always get the DoF with a fast lens, but am not above using lens blur to smooth out the bokeh if it looks a bit unpleasant (example would be where you have very small point source lights in the background, a less than stellar lens, and a mass of doughnuts distracting from the subject; if that can be ameliorated to make a better composition then it’s valid IMHO. Not everybody can afford mega expensive lenses that do this just right by themselves). Also, sometimes you might want the background quality you’d get from f2.8 but have to shoot at f4 or f5.6 to keep the entire subject in focus and compromise the amount of blur in the background. That’s also what I’d consider a valid use of extra post-pro blurring. If the end result looks right and not faked, who cares other than perfectionists?
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