**Image smoothing using an isotropic Gaussian filter**I want to smooth an image using an isotropic Gaussian filter with
standard deviation of =F3x, =F3y =3D 3.
To achieve this, can I use the fspecial function to create the
smoothing filter as follows:
gauss_filter =3D fspecial('gaussian', [x y], 3);
With [x y] being the size of the filter to apply to the image. If not,
what should I be using instead?
Also, what is the relationship between the number of filter samples
required and the standard deviation used?
Thanks.
...

**what is the cutoff frequency for Gaussian filter in Matlab imaging processing?**Hi all,
This is a continuum of the question I post one moment ago. I've obtained a
11x11 impulse response for that 2D low pass Butterworth filter of 7th order
and 0.2 cutoff frequency(normalized frequency range [-0.5, 0.5])...
My friend claimed that the following 11x11 h impulse response have negative
values in it so it is no good for image filtering... (btw, why are there
negative values? )
He suggests that I forget these fancy filters and use a plain Gaussian
filter for low pass filtering... however I looked into the "fspecial"
command in Matlab image toolbox... and I ...

**padding gaussian matrix for 2d filtering image process**I must do a Gaussian Filter on image,
I have matrix data image in a 100x100 matrix.
I generate a 7x7 gaussian matrix for filtering,
how do I padding the gaussian matrix for obtain a 100x100 matrix ?
with zeros value around gaussian value ?
thank you so much.
anyone can help me ?
...

**Filters : a library implementing image filters and image processing functions**Dear members,
I would like to inform you that we have released our last version of
the open source library "Filters". We will appreciate your feedback.
link : http://filters.sourceforge.net/
Regards
In short, no source code = crap.
Come back when you've got something real to download, a few demos
and some API's don't equate to much these days...
edurand wrote:
> Dear members,
> I would like to inform you that we have released our last version of
> the open source library "Filters". We will appreciate your feedback.
> link : http://filters.so...

**(image process) are there any guidelines on how to design good filters to enhance an image?**dear all,
I am facing the following problem that I need your help:
We have in our experiments some special images need to be processed. My task
is to look at these images and see how to improve/enhance them. In fact we/I
have no idea on how much enhancement we can get.
So what I've done in the past month is to play with different kind of
filters to try on the images. We use PSNR as judgement. It turns out I found
a Gaussian 3x3 filter has particularly high enhancement to the images,
comparing with other filters provided by Matlab, such as "laplacian",
"averaging"...
...

**image processing and filtering**Hi,
My program is to read some images and then high pass
filter to filter the image and plot out the rms values.
I’m able to read and display the image. But the filter got
problem.
The error message:
??? Undefined function or variable 'filterarray'.
Error in ==> D:\MATLAB6p5p1
\work\signalimage\FocusImages\new.m
On line 47 ==> lengthoffilter=length(filterarray);
I can’t continue. Anybody know how to troubleshoot?
Below is the program.
Thank you.
Regards,
Sem
--------------------------------------------------
clc;
close all;
clear all;
for picture=1:...

**Applying a gaussian filter to an image**Hi,
I am quite new to Matlab. Is there a built-in function to apply a
gaussian filter over a color image?
If not, any hints on how to do it?
Also, if there is a built-in function, can I tell it to handle edges
differently (like, using kernel renormalization?)
Thanks a lot in advance.
Did you try this?
filterMask = gausswin(dy) * gausswin(dx)';
imageOut = filter2(filterMask, imageIn);
Where dx and dy is the size of the rectangular filter mask.
I would do the edge handling manually by padding, but maybe there is
a better way to do that.
Regards
Markus
[url=http://zvxcxw.googlepages...

**image processing**Hi,
If I am using scipy.ndimage.gaussian_filter() for filtering an image,
how to do the inverse filtering? In general how to do this using
scipy.ndimage?
Thanks
suresh
In article <5bfefbb6-89a8-49f6-9f02-7d36dfbc0f16@c29g2000yqd.googlegroups.com>,
suresh.amritapuri <suresh.amritapuri@gmail.com> wrote:
>
>If I am using scipy.ndimage.gaussian_filter() for filtering an image,
>how to do the inverse filtering? In general how to do this using
>scipy.ndimage?
http://projects.scipy.org/mailman/listinfo/scipy-user
--
Aahz (aahz@pythoncraft.com) &...

**Gabor filters in Image Processing**i have to filter my images by Gabor filters. I write my Gabor
function. It takes the parameters of "Size", "Standard Deviation",
"Period" and the "Orientation of gabor shell".
My purpose is to find rectangles in the images. After filtering, i
will binarize my images, and i will approximately find the places of
rectangles in my images.
That seems ok. but every images have different backgrounds and
illumination level. Although i have done preprocessing, the output of
filtering is not good. I have chose the parameters of filters by trial
and err...

**IMAGE PROCESSING**Hi,
I have an RGB image and without converting it to grayscale I want to
do median filtering. Is it possible , if so how ?
I tried to create the median filter but it give me following error
Function ORDFILT2 expected its first input, A, to be two-dimensional.
Error in ==> ordfilt2>ParseInputs at 135
iptcheckinput(A, {'numeric','logical'}, {'2d','real'}, mfilename,
'A', 1);
Error in ==> ordfilt2 at 51
[A,order,domain,s,padopt,msg] = ParseInputs(varargin{:});
Error in ==> medfilt2 at 57
b = ordfilt2(a, order1, domain, padopt);
Erro...

**matched filtering (image processing)**Hi,
Have anyone done any image processing function called matched
filtering. I have two input images (same size). The output should be
the correlation value between two image. I tried corr2 function but
it doesn't work well when the image is shifted to left or right (not
shifting invariant). I hope that matched filtering will solve this
problem.
thanks
xcorr2 or conv2 should do the job, if you design your matched filter
accordingly.
/Johan
yo wrote:
> Hi,
> Have anyone done any image processing function called matched
> filtering. I have two input images (same size). T...

**image processing Gaussian smoothing**why Gaussian smoothing is commonly used with edge detection?
what is the most suitable smoothing method for __edge detection algorithm? Is it Gaussian smoothing? If so, why?
...

**sinc filter for image processing**Hi,
I want to use sinc filter for image processing. As I understand for its theory this can be suitable for edge detection operation.How can I do this in Matlab? Could you help me about this operation?
Thanks.
On Sep 22, 4:28=A0am, "elysion87 " <saki...@gmail.com> wrote:
> Hi,
>
> I want to use sinc filter for image processing. As I understand for its t=
heory this can be suitable for edge detection operation.How can I do this i=
n Matlab? Could you help me about this operation?
> Thanks.
-----------------------------------------------------------
Yes. Set u...

**Image processing: high pass filter**Hey guys. I kinda need some help here. I'm doing some image
processing and I'm programming some filters. Here's the
case of a high pass filter, for instance with a 5x5 kernel
which has this form (I stole it from the IPP):
0 -1 -1 -1 0
-1 -1 -1 -1 -1
-1 -1 21 -1 -1
-1 -1 -1 -1 -1
0 -1 -1 -1 0
So, the negative coefficients here may turn the result of
applying the kernel to be negative for a particualr pixel,
or maybe bigger than 255. Is there any normalization
technique?
I tried uint8 but the results are far worse than what I get
when applying the filter in IPP
Than...

**CVS for image processing and adaptive filter**Hi my name is Alam, and now i'm working for my final project in my university.
My task is to set up a vision based tracking system. It use a single
firewire camera to detect the presence of an object using some image
processing algorithm that give an information about object coordinate
position. I use this information as the input for Kalman Filter so that
i can predict the object position for the next state of my system.
I just want to know if I can do that job using LabView and CVS 1454 (
because my supervisor order me to use it ). If it is possible I also
want to know how can i send ...

**matlab image processing matched filter**hi to all
Im new to image processing and also to matlab. I have a project which needs to extract blood vessels from retinal image by using matched filtering and It looks like I have to desgin one but I have no idea what is a matched filter. Can some please explain me image processing with matched filtering
thank you
ANIL
Why do you need to use a matched filter? Why not use any method that
you can think of that will work?
If it's your homework problem, then review your notes from the class
lectures or ask your professor.
If you have a MATLAB question, such as how to use im...

**processing and filtering image spot satelital**i can any process with matlab to image spot5
satellite.
You have any practice with this?
tank regards
...

**the point of passing through a filter in image processing**Hi,
I have a basic question on image processing, after FT, I got the casted
image on different colors, or different freq. Next is to pass through a
filter to get the freq that I want. I am wondering, I can just pick up
any freq I want, and the band of freq I want. Why do I have to
construct a filter? Is it really needed? Or how a filter is being used
in image processing?
thanks
PZ
PZ wrote:
> Hi,
>
> I have a basic question on image processing, after FT, I got the casted
> image on different colors, or different freq. Next is to pass through a
> filter to get the freq tha...

**Using an image mask as a filter for video processing**I am trying to measure the change in area of an object for a neurophysiology assay. Currently, I load a video, crop it, apply a rgb filter to the frames of interest and pass that information onto bwlabel. I use bwlabel and regionprops to calculate the change in area for each frame, saving the data as a vector providing me with a nice curve. My problem is this: i want to calculate the area of an individual object, while excluding other objects in frame within the parameters of rgb filter . The rgb filter works okay but it can be too lax or stringent depending on the circumstances.
I want ...

**image processing face tracking for particle filter**somebody ever used particle filter(PF)?
i write face detection code and particle filter code
the particle filter used random number made initial value simulated
how can i make face detection and PF combine ?
...

**image processing: FFT and low pass filtering**As a beginner of image processing, it is asked from me to write C
codes that take FFT(Fast fourier transform) of a 256X256 image then
passing the image from a low pass filter and at the end taking
inverse transform to obtain the original filtered image.
i thought that Matlab can help me on this way: if i write the m
code of the programme and then using the Matlab compiler convert that
to C code. But i am having difficulties to obtain H(u,v): low pass
filter in fruquency domain.
Could somebody help me?I will appreciate.
Thanks
Eyup wrote:
>
>
> As a beginner of image process...

**Region of Interest Filtering in Image Processing Toolbox**I am trying to conduct a bwlabel and then a subsequent
regionprops(centroid) to extract the centroid of a blob. However, I
need to limit where bwlabel searches for these objects. I am having a
very difficult time simply masking the image so the bwlabel only
searches where a poly region that I specify, any help would be
greatly appreciated!!!
Wally Davinport wrote:
>
>
> I am trying to conduct a bwlabel and then a subsequent
> regionprops(centroid) to extract the centroid of a blob. However, I
> need to limit where bwlabel searches for these objects. I am having
> a
> very...

**image processing filters and pixel shader**hi I am learning to use pixel shader to do digital image processing on
large scientific images. What I am doing right now is to load a huge
texture into GPU and write pixel shader programs to process it.
Quesitons:
1. Is it true that the texture size is limited by video memory? I am
loading large images that contains easily 100M+ pixels (each pixel
contains 3 channel 32-bit float). The problem is I can not load only a
part of the image into video mem. The algorithm I am working on is a
"local" processor that will cause different result if I load the
images piece by piece.
2. I can ...

**Server-side image processing using Photoshop filters**Hi,
Does anyone know of a good way to do server-side image processing, and
take advantage of Photoshop's filters (e.g. drop shadow, inner glow,
etc.). Basically we need the image quality of Photoshop, but all the
images are processed in a multi-threaded non-GUI service. I know
Photoshop does expose an automation interface, but that would require
PS to be installed on the server, and moreover it is not suitable for
high-performance use (due to the fact that it needs a GUI and is a
single-use COM server).
Any suggestions would be appreciated.
Thanks.
"r4d0n" <mqtest@hotma...