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Can someone give me a good example of when you would use this? And why would
you use it opposed to using say, the Gausian Blur?
Please and Thanks :))
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| Spandex Rutabaga 2005-09-12, 11:21 pm |
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"Jo=EBlle" wrote:
>=20
> "Sonja" <Bonesy8@REMOVETHIScharter.net> wrote in message
> news:4325bc26$1_1@cnews...
When you want an average. For example, you would use the Average filter
if you wanted to calculate the average color of some part of the image
instead of simply to blur the image. The Average filter also produces
a blur with a slightly different appearance so it might be desirable
sometimes for artistic reasons.
[color=darkred]
> And why
[color=darkred]
> As far as I am concerned, Caussian Blur is more 'aggressive'.
It isn't. It only seems that way because the settings of Average
(aperture) and Gaussian Blur (radius) filters cannot be directly
compared. Both kinds of blurs combine the color of a given pixel with
the colors of surrounding pixels. Which pixels count as "surrounding"
depend on the filter's setting - more pixels for a bigger setting.
Gaussian Blur uses a bell-shaped weighting so that the pixel of
interest has most weight and surrounding pixels have less and less
weight the further they are from the pixel of interest. In the Average
filter the pixel of interest and all surrounding pixels have the same
weight. In that sense Average is actually more "aggressive" than
Gaussian because the surrounding pixels have more effect on the pixel
of interest. To make it more interesting efficient implementations of
Gaussian filters use the Average filter internally for very large blur
radii :-) I think PSP's Gaussian Blur filter does this since it
suddenly got much faster between PSP 7 and PSP 8.
> So if you want
> more control, use Average Blur.
> Blur and Blur More settings can't be controlled, I never use those.
Yes they can. Duplicate the layer, apply the blur, modify the opacity
to control the strength of the effect. This is a lot like Photoshop's
fade procedure.
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| Joëlle 2005-09-13, 7:20 am |
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"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message
news:432614B7.E9406865@agabatur.xednaps...
"Joëlle" wrote:
>
> "Sonja" <Bonesy8@REMOVETHIScharter.net> wrote in message
> news:4325bc26$1_1@cnews...
When you want an average. For example, you would use the Average filter
if you wanted to calculate the average color of some part of the image
instead of simply to blur the image. The Average filter also produces
a blur with a slightly different appearance so it might be desirable
sometimes for artistic reasons.
[color=darkred]
> And why
[color=darkred]
> As far as I am concerned, Caussian Blur is more 'aggressive'.
It isn't. It only seems that way because the settings of Average
(aperture) and Gaussian Blur (radius) filters cannot be directly
compared. Both kinds of blurs combine the color of a given pixel with
the colors of surrounding pixels. Which pixels count as "surrounding"
depend on the filter's setting - more pixels for a bigger setting.
Gaussian Blur uses a bell-shaped weighting so that the pixel of
interest has most weight and surrounding pixels have less and less
weight the further they are from the pixel of interest. In the Average
filter the pixel of interest and all surrounding pixels have the same
weight. In that sense Average is actually more "aggressive" than
Gaussian because the surrounding pixels have more effect on the pixel
of interest. To make it more interesting efficient implementations of
Gaussian filters use the Average filter internally for very large blur
radii :-) I think PSP's Gaussian Blur filter does this since it
suddenly got much faster between PSP 7 and PSP 8.
> So if you want
> more control, use Average Blur.
> Blur and Blur More settings can't be controlled, I never use those.
Yes they can. Duplicate the layer, apply the blur, modify the opacity
to control the strength of the effect. This is a lot like Photoshop's
fade procedure.
Thank you SR from the YY Dept. :-))
I shall read this very carefully.
:-)
Joëlle
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Sonja wrote:
> Can someone give me a good example of when you would use this? And
> why would you use it opposed to using say, the Gausian Blur?
>
> Please and Thanks :))
Also Gaussian Blur gives the same sort of blur as an out of focus lens
does.
--
Tim Morrison
C-Tech volunteer
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"Joëlle" <makingmerry@inSussex.com> wrote in message
news:4325cfdc_1@cnews...
>
>
> "Sonja" <Bonesy8@REMOVETHIScharter.net> wrote in message
> news:4325bc26$1_1@cnews...
>
> As far as I am concerned, Caussian Blur is more 'aggressive'. So if you
> want more control, use Average Blur.
> Blur and Blur More settings can't be controlled, I never use those.
>
Thanks Joelle
I can see the difference in the posted images but I am still not real clear
of "real world" example of why you would use which and when.
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"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message
news:432614B7.E9406865@agabatur.xednaps...
"Joëlle" wrote:
>
> "Sonja" <Bonesy8@REMOVETHIScharter.net> wrote in message
> news:4325bc26$1_1@cnews...
When you want an average. For example, you would use the Average filter
if you wanted to calculate the average color of some part of the image
instead of simply to blur the image. The Average filter also produces
a blur with a slightly different appearance so it might be desirable
sometimes for artistic reasons.
I am still not getting it... other than the fact they apply differently
[color=darkred]
> And why
[color=darkred]
> As far as I am concerned, Caussian Blur is more 'aggressive'.
It isn't. It only seems that way because the settings of Average
(aperture) and Gaussian Blur (radius) filters cannot be directly
compared. Both kinds of blurs combine the color of a given pixel with
the colors of surrounding pixels. Which pixels count as "surrounding"
depend on the filter's setting - more pixels for a bigger setting.
Gaussian Blur uses a bell-shaped weighting so that the pixel of
interest has most weight and surrounding pixels have less and less
weight the further they are from the pixel of interest. In the Average
filter the pixel of interest and all surrounding pixels have the same
weight. In that sense Average is actually more "aggressive" than
Gaussian because the surrounding pixels have more effect on the pixel
of interest. To make it more interesting efficient implementations of
Gaussian filters use the Average filter internally for very large blur
radii :-) I think PSP's Gaussian Blur filter does this since it
suddenly got much faster between PSP 7 and PSP 8.
Ok.. so what do the Blur and Blur More do (or not) do that Gaussian and
Average don't do?
Thanks Veggie!!
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"Tim" <timmorr64@XremoveXhotmail.com> wrote in message
news:43268c64_2@cnews...
>
> Sonja wrote:
>
> Also Gaussian Blur gives the same sort of blur as an out of focus lens
> does.
Thanks Tim!
UG.. I am still confused! LOL
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| Joëlle 2005-09-13, 7:20 am |
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"Sonja" <Bonesy8@REMOVETHIScharter.net> wrote in message
news:43269960_2@cnews...
>
>
> "Joëlle" <makingmerry@inSussex.com> wrote in message
> news:4325cfdc_1@cnews...
[color=darkred]
> Thanks Joelle
> I can see the difference in the posted images but I am still not real
> clear of "real world" example of why you would use which and when.
>
>
I don't think anything is 'set in concrete', I play aound with the settings,
if I like them I use them. If like them a lot I make a preset.
In PSPX there is even more to play with, so I am having fun :-)
Joëlle
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| Spandex Rutabaga 2005-09-13, 7:52 pm |
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Sonja wrote:
> Ok.. so what do the Blur and Blur More do (or not) do that Gaussian and
> Average don't do?
I don't know exactly since I'd have to work at Corel to know. My guess
is that both Blur and Blur More use a very local concept of the
surroundings of a pixel - perhaps a 3 x 3 pixel window - and differ
in the weights given to the surrounding pixels relative to the central
pixel of interest. Blur More would give these a higher weight than
Blur does.
> Thanks Veggie!!
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| Spandex Rutabaga 2005-09-13, 7:52 pm |
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Sonja wrote:
> UG.. I am still confused! LOL
It must all seem like a blur.
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"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message
news:4326E47B.AC5E8088@agabatur.xednaps...
>
> Sonja wrote:
>
>
> I don't know exactly since I'd have to work at Corel to know. My guess
> is that both Blur and Blur More use a very local concept of the
> surroundings of a pixel - perhaps a 3 x 3 pixel window - and differ
> in the weights given to the surrounding pixels relative to the central
> pixel of interest. Blur More would give these a higher weight than
> Blur does.
>
Ok I think I might actually be getting this now... I am sure you will tell
me if not right? LOL
So Blur and BM use a small squared area and then Average just uses each
single
pixle surrounding the center? ????
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| Spandex Rutabaga 2005-09-13, 7:52 pm |
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Sonja wrote:
> Ok I think I might actually be getting this now...
You aren't yet.
> I am sure you will tell me if not right? LOL
If you insist.
> So Blur and BM use a small squared area and then Average just uses each
> single
> pixle surrounding the center? ????
It's pixel, not pixle, and the answer is no I'm afraid. Let's try this
one more time. Imagine either a 3 x 3 pixel window or a 5 x 5 pixel
window like the ones shown below centered on the pixel marked with a
@. This @ is put successively on each pixel of the image so that
the positions marked with letters of the alphabet lie over surrounding
pixels in the image. (3 x 3 or 5 x 5 windows aren't the only ones
possible. For example, the Average filter goes up to a 31 x 31 pixel
window. Obviously you have to do something special when @ is placed
over an edge pixel of the image since part of the window would be
outside the image. Usually you mirror image pixels across the edge of
the image to fill up the filter window.)
A B C I J K L M
H @ D X A B C N
G F E W H @ D O
V G F E P
U T S R Q
Let's use the 3 x 3 pixel example to start with. For every pixel in the
image the new filtered value at the location @ is given by:
New@ = (w x A + w x B + w x C + w x D + w x E + w x F + w x G +
w x H + Old@) / (8 x w + 1)
The pixel values A through H are multiplied by a weight w, added
together, added to the old value at the pixel of interest @, and all
this is divided by the sum of the weights in the window. For the
Average filter the weight w is 1 so you just add up all the pixel
values in the window and divide by 9. The values at pixels A through H
contribute the same as the value at @ to the result value. Now imagine
that we used a weight w equal to zero. Pixel values A through H would
be multiplied by zero and would have no effect. As a result New@ would
be the same as Old@ and the filter would do nothing and produce no
blur. To produce a slight blur (as for the Blur filter) we need a
value of w greater than zero but not much greater. This would change
the center @ pixel value but not much. To produce a stronger blur we
need w to be much bigger but less than 1. (If it were 1 we would have
the Average filter, not the Blur More filter.) With a bigger weight
the surrounding pixels affect the center pixel more, so causing a
bigger blur.
The 5 x 5 example works the same way but is long and complicated to
type out in detail. Instead of 9 pixel values we have to take into
account 25 pixel values. However, using this example we can understand
one thing. The innermost pixels A through H can have one particular
weight, say w1, but the outermost ring of pixels I through X can have
a different weight w2. (The divisor would be 8 x w1 + 16 x w2 + 1) In
the case of an Average filter w1 = w2 = 1 (and the divisor is 25).
In other words all the weights are 1 no matter how far the ring of
pixels lies from the center pixel @. In the Gaussian Blur filter the
weights decrease from one down to zero the further a surrounding ring
lies from the center pixel @. For the 5 x 5 pixel example the weight
w1 would be less than 1, the weight w2 would be less than w1, and the
weight of pixel values outside the window would be zero.
The bottom line on all this is the following. Blur filters manipulate
the amount of blur in two ways. One way is to change the size of the
filter window to include fewer or more surrounding pixels. This is
what the Aperture setting of the Average filter and the Radius setting
of the Gaussian Blur filter do. The other way is to work with a fixed
size filter window and mess with the weights of the surrounding pixel
values. This makes the difference between Blur and Blur More. If you
mess both with the window size and with the way the weights change in
the window with distance from the center then you get the difference
between the Average and Gaussian Blur filters. The Average filter
has all identical weights that don't change with distance from the
center while the Gaussian Blur filter has weights that decrease away
from the center.
I hope this helps. I don't know how to explain it without recourse to
arithmetic. You can type values into the User Defined filter to
experiment with some of these ideas. What you type into the boxes of
that filter are the weights. Just make sure that Divisor is the sum of
the weights or you will change the brightness of the image. The easy
way to get the right divisor is to type in your weights and then press
the Compute button. (When some of the weights are negative you start
creating emboss or edge enhancement or edge finding filters.)
Many image processing filters work in the way described. Others such
as Median, Erode or Dilate depend on sorting the pixel values in the
filter window and picking a specific location in the sort as the
filter result value. Other filters such as the Edge Preserving Smooth
or Salt and Pepper filters I would guess to be much more complicated.
That's probably why they are slow :-)
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"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message
news:4326E49B.4169719B@agabatur.xednaps...
>
> Sonja wrote:
>
>
> It must all seem like a blur.
<moan> ROFLMAO
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| Spandex Rutabaga 2005-09-14, 7:56 pm |
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Sonja wrote:
> Wanted to give you something in appreciation for the help but didn't have
> time to wrap it. ;)))
Thank you. Most of the time people throw manure at me.
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| SAGOTEB 2005-09-15, 7:32 am |
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"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message news:43283404.4BBA46B0@agabatur.xednaps...
>
> Sonja wrote:
>
>
> Thank you. Most of the time people throw manure at me.
Manure makes vegetables stronger, so be gratefull!. ;-))
>
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