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View Full Version : Controlling filter intensity with something like a mask?


NightLord
11-23-2005, 06:57 AM
Hi people,

I've been puzzled about this for a while now and I can't seem to find a 'real' solution. It seems to be quite a basic thing so I hope someone here can help me out.
I'm taking a shadow as an example to illustrate my point, please refer to the example I made (just a quick one :D).
The example in the picture has a dropped shadow that I transformed to match the perspective, then applied a mask with a radial gradient to make it fade. Close to the object the shadow must be sharp, farther away it needs to be blurry.

I imagine that to achieve this, some type of gradient applied to a filter would be perfect, like a mask, but then masking not the opacity but the actual amount of blur.
After some experiments I came up with a path in line with the shadow (see example), that I stroke with the blur tool (with simulate pressure on). After about 20 times, it seems to do start to do the job, buit it is surely NOT really what I wanted to do. It is clumsy and a rather imperfect way of doing it. Besides, the blur tool is just not strong enough for this, and when a larger picture is involved this method is useless.

Does anyone know how to do this properly? I used this shadow as an example, but this would allow beautiful effects when done with other filters. :)))

Thanks in advance!

/NL

sPECtre
11-23-2005, 07:22 AM
If you use CS or CS2, then the lens blur could be your weapon of choice ;D

If not, look at this thread for a work-around that could work with other filters: http://photoshoptechniques.com/forum/showthread.php?t=169&highlight=blur+challenge

Have fun, compatriot!

Stroker
11-23-2005, 11:37 AM
This is something that I've been thinking about doing myself. There is an odd 'bug' in FilterMeister that allows 'loading' of an Alpha channel. You know, an accidental feature that wasn't exactly a bug. Didn't Jelly ask about this not too long ago?

Depending on the holiday, I might knock out a quick proof of concept. We'll see how a simple box blur fares.

NightLord
11-23-2005, 04:03 PM
Thanks for the link sPECtre, I didn't find that one myself.
Like Raphael stated, most of the 'workarounds' do not give a real gradual blur. And a gradient selection with gaussian blur doesn't either... The idea of using a growing selection and blurring over and over again crossed my mind before, and now I got it working quite nicely.

The million dollar question however: how to generalize this idea, like the "amount masking" Greg was talking about in that thread...

I didn't get your lens blur idea working for me sPECtre, care to elaborate?

Stroker, thanks for your reply, I will be looking into FilterMeister for sure... I've got no experience with that one so I'll be back on this when I tried it

Thanks again for the help guys :D

/NL

sPECtre
11-23-2005, 04:21 PM
In CS and CS2, you've got a blur filter that can vary its amount of blurring depending on a layer mask, or transparency. It is called lens blur... (google it)

MrJelly
11-23-2005, 04:24 PM
Check it out, NightLord:

http://www.photoshoptechniques.com/forum/showthread.php?t=15961&highlight=alpha+blur