What’s the Deal With the New Lens Blur Filter?

H
Posted By
haverbach
Jan 18, 2004
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767
Replies
18
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Closed
I restore old photos. In many portrait-like images, I blur the background somewhat so as to de-emphasize it in favor of the main portrait foreground. (Select the background, then apply Filter>Blur>Gaussian Blur)

Photoshop 8 now has a new function: Lens Blur filter.

I’ve read everything Adobe provided on the Lens Blur filter, but the manual says nothing and Photoshop “Help” provides only sparse application instructions. I tried, tested, examined and experimented with the Lens Blur filter, but cannot see any advantage over the old method.

I had hoped that this new function would blur the selected image more and more as one looks past the foreground image and views deeper and deeper into the background, i.e., similar to true depth perception. I understand that there are some old, much-involved techniques to accomplish this, but I was hoping that the new Lens Blur filter was a new, high-tech solution to this depth-blurring goal.

What have others found with respect to the new Lens Blur filter? Am I missing something?

Thank you.

Howard

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MV
Mathias_Vejerslev
Jan 18, 2004
Howard,

I had hoped that this new function would blur the selected image more and more as one looks past the foreground image and views deeper and deeper into the background, i.e., similar to true depth perception.

And how, exactly would this new technology be able to determine whats foreground and what is background, after the photo has been taken??

I understand that there are some old, much-involved techniques to accomplish this, but I was hoping that the new Lens Blur filter was a new, high-tech solution to this depth-blurring goal.

It´s called masking, and, although ‘old techniques’ theyre still essential to most photoshop techniques.

I think I can guarantee there wouldnt be an automatic ‘depth perceptio blur’ any time soon. I dont know how exactly Lens Blur works, as I dont have CS yet, but hopefully it gives more of a natural coma effect than plain gaussian.
JB
Jonathan_Balza
Jan 18, 2004
You guys are missing a little bit of it. I LOVE the lens blur filter. Almost as good as actually having taken the photo that way.

The new lens blur really does accomplish the "depth perception" blur MUCH better than any version of PS before, including many more settings and versatility.

The key is creating a "Depth Channel" in an alpha channel. When creating this channel, keep in mind that by default, the black portions of the channel are not blurred at all, and white is blurred to the amount of the radius setting. To access this feature in the lens blur dialog, select your Alpha channel in the Depth Map: Source drop down box. Then you will see the true power of the lens blur feature.

Among the other new functionality in the lens blur is a true "gradiant blur" as evidenced by my tutorial here. <http://www.balzasteel.com/tutorials/gradientblur.shtml> This was not easily achieved at all in previous versions of PS, even with the mask and blur technique used to simulate it.

Besides all of that, there are other features that are useful: – Specular Highlights (Commonly seen by sunlight on waves) – Noise (A true photograph even though blurry, would still have noise on it.)
JR
John_R_Nielsen
Jan 19, 2004
How is this filter? How does it compare with the Sakurai IrisFilter (http://www.reiji.net/index-e.html)?

I played around with the Iris filter demo and liked it, but can’t justify the price for something I would only use occasionally.
MM
Mick_Murphy
Jan 19, 2004
One huge difference is speed and I have no problem with speed in CS in general. Try using lens blur on a 50Mb image. YAWN! Definitely play with a low res version if you intend to use this. And the dialog box is another one which forgot that some people use large fonts in Windows.
JB
Jonathan_Balza
Jan 19, 2004
Just looking at the example images – without testing the demo, the lens blur filter at least matches what IrisFilter produces.

I agree that speed on PS’s Lens Blur is an issue for sure. But I can’t imagine that this is a very simple filter to apply. I’d imagine it’s one of the more math-intensive filters out there. (Does anyone know for sure? Chris maybe?) Oh yeah, are you referring to the speed in IrisFilter or the speed in Lens Blur?
TM
Thomas_Madsen
Jan 19, 2004
And the dialog box is another one which forgot that some people use large fonts in Windows.

Yep. That’s generally a big problem in CS.


Regards
Madsen.
H
haverbach
Jan 19, 2004
To Mathias Vejerslev:

As you can see, your smart-ass response was to no effect, and merely reflected your ignorant demeanor. As was pointed out by Mr. Balza (in response #2 above), the recently-introduced lens blur filter apparently does have new capabilities (egg on your face), albeit some significant practice may be required to unearth and master them. But then again, one would not expect you to know of these if you don’t yet have CS, notwithstanding that you deemed it your place to comment anyway.

Warmest regards,
HSA
PC
Patty_Clarke
Jan 19, 2004
Howard,

I think you misinterpreted Mathias’ words as "smarta$$".

""It´s called masking, and, although ‘old techniques’ theyre still essential to most photoshop techniques. I think I can guarantee there wouldnt be an automatic ‘depth perceptio blur’ any time soon. I dont know how exactly Lens Blur works, as I dont have CS yet, but hopefully it gives more of a natural coma effect than plain gaussian. ""

I’m new to CS, and today had my first experience with the lens blur filter. I don’t understand it "yet", but as Mathias stated "masking" is an important function of lens blur.

I plan to check out Jonathan’s tutorial.

The lens blur menu is very complex (at least for my level of understanding), but it seems to have incredible capability. You can combine different layer masks to achieve the lens blur in a pretty specific area. You can combine a luminance mask with a gradient or gaussian blur and then further fine tune your selection by "painting away" other areas.

Patty
AP
Alpha_Papa
Jan 19, 2004
Hi Patty – follow the tutorial it is very easy to grasp and apply and hence, understand one application of the tool.

The addded benefits of lens blur are as already mentioned, the included noise function which makes adding noise to the blur easier than chosing a secondry filter on a selection or layer.

Also note the inclusion of the threshold feature too, which adds endless possibilities to alternate effects.

Adam.
MV
Mathias_Vejerslev
Jan 19, 2004
"haverbach"

You are right about one thing: My post didnt accomplish anything at all.

Mathias
PC
Pierre_Courtejoie
Jan 19, 2004
Haverbach, Mathias’ answer is NOT a smarta$$ one!

In fact, Jon’s post corellates exactly what Mathias said; you DO need to create a alpha channel manually (Mathias used the term "masking", and alpha channels are one form of masking) to allow the LensBlur filter to apply different blur settings.

Lensblur has NO automatic detection system of what is in front and what is in the background… it has, however, the ability to aply in one pass different strenghts of blur in an image, based on the aforementionned alpha channel.

Mathias never said that there was no other improvement in the filter, please re-read his post.

Before, you had to re-launch the blur filter with different selections/masks/alpha channels to achieve a better sensation of depht. (So the speed of the filter should be compared to the multi pass approach of the old method.)

There is a lens blur tutorial in the Adobe Expert Center: < http://studio.adobe.com/tips/tip.jsp?p=1&id=411&xml= phs8lensblur>

Look also at <http://www.photoshopuser.com/photoshopcs.html> for more info on PSCS’ new tools

Childish comments such as "egg in your face" are out of context, when somene posts good information to try to help you, and you misunderstand their answer. An excuse should be made, IMHO
MV
Mathias_Vejerslev
Jan 19, 2004
Nah, it´s OK, I probably did come across as a bit snubby; sometimes my posts are a bit hastily written. Water under the bridge.
BH
bryan_hughes
Jan 19, 2004
As a sidenote, there’s a feature (with a depth map present) where a cross hair appears in place of the cursor, and the start point of a blur can be set to any point the user sets the mouse click to. As for speed, try the two preview modes, and keep in mind that certain adjustments (specular highlights comes to mind) are more processor intensive than others. Hope this helps, enjoy. -Bryan
H
H._Averbach
Jan 19, 2004
Patty and Pierre,

Thanks for your responses. But note that in my original post I made mention that I read all that Adobe had to offer (in the manual and “Help” screens) regarding the Lens Blur filter. Moreover, as one who restores old photos (for several years), surely it can be inferred that I understand masks and masking. (Any by the way, simple selection techniques, such as with the lasso tool, will also save an Alpha Channel through which the Lens Blur filter will work.) After all, even applying the old standby Gaussian blur to a background — what I’ve done for years — will require either a Lasso selection, mask, Layer via Copy, or such.

Thus, according to Mr. Balza – who kindly provided a very helpful response (what one would think is the purpose of this forum) – is to create a “Depth Channel”. I don’t yet know how to do so (I had sometimes used the repetitive technique described by Pierre), but it now certainly seems that creation of a Depth Channel is the precursor to a successful implementation of the Lens Blur filter.

So, Pierre, I respectfully disagree with you that the “egg on your face” comment was out of place. The poster to whom it applied in fact provided no useful information, whereas Jonathan Balza did so in just a couple of on-point sentences. And, of course, the information you provided in your reply is also most helpful – in direct contrast to that provided by Mr.Vejerslev, which, as he, himself, subsequently stated was “snubby … and hastily written”. I seldom post anything here, but to the extent of any future contributions, it seems a favorable omen that Mr. Vejerslev will not be responding.

In any event, thank you Jonathan Balza, Patty Clarke, and Pierre Courtejoie. I suppose that now would be a good time to master creating a Depth Channel.

HSA
JB
Jonathan_Balza
Jan 19, 2004
The Adobe Studio link that Pierre posted has an example of what a "depth channel/mask" might look like about half-way down the page. They can get complex fairly fast but you might be able to get the idea.

For the most part, the guiding principle is this: The farther away an object is, the lighter the channel should be.

Or, you could look at it the way they do in the example: What you want to be in focus gets the Black, and then whatever is farther/closer gets gradiated out towards white.
DM
dave_milbut
Jan 20, 2004
I seldom post anything here, but to the extent of any future contributions, it seems a favorable omen that Mr. Vejerslev will not be responding.

and that’s your loss because mathias is one of the best (and nicest) people you could have helping you solve a PS problem. the "egg on your face" is yours for jumping down his throat w/o realizing there may be more than one interpretation to a written comment.
PC
Philo_Calhoun
Jan 20, 2004
A depth channel would be just an alpha channel. I concur that Mathias has great knowledge of PS and has been a great asset for this forum. But as he explained, he doesn’t have PS CS, so he would be unlikely to give much information about the nuances of the lens blur feature other than remind people that a realistic effect would depend on a realistic selection (alpha channel). If one does not like an answer, one can just ignore it. Remember that anyone who answers does so for free and out of the desire to help.
PC
Pierre_Courtejoie
Jan 23, 2004
The reason of my post has been explained in the two last posts.

(BTW, Hello, Jon!, and thanks for the simple explanations!)

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