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Help regarding Rectangle/Square detection algorithm
Chandresh Chaudhari from United States  [6 posts]
10 years
Hi Steven,
Thanks for your suggestion. Please find the sample images, RGB and BW, for your reference. I have converted RGB in to BW using matlab
I=imread('door6.bmp');
imview(I)
Ibw=im2bw(I,0.2);
imview(Ibw)

Below is the question, Participation of all members is aappreciated:

Hi all
I have a video data stream recorded by a camera mounted on a robot in
indoor environment. I have created an object in Matlab that acquires
the video data and using matlab function I am able to get the image
frames from the data so now I have an image that contains rectangle (or
square) number plate. I want to cut this rectangle number plate area
from the image to do further analysis. How can I do it in Matlab? Your
help is greatly appreciated as my work is more related to path
planning. Any kind of help that makes my work more specific is welcome.


Thanks & regards,


Chandresh

Forum did not support bmp so now here are the jpg images
Chandresh Chaudhari from United States  [6 posts]
10 years
Sorry about the two posts for one message but Forum did not support bmp so now here are the jpg images.






Thanks,

Chandresh
Anonymous 10 years
Chandresh,

To continue along the lines that you started out on ... use the thresholded image to create a mask that you would use against the current image. For example, you would need to smooth the edges of your image by getting the convex hull of the edges like in  



and then fill the holes in the object to get



then you could check the area of each object greater than say 100 pixels to be close to its bounding box .. i.e. check that the object is square to some degree. Area is how many pixels are in a single object compared to the bounding box area which is defined as (xmax-xmin)*(ymax-ymin). If the two are close then you have a squarish looking object. Filtering for that you are left with



which can then be seen as a mask against the original image to finally give you



Does that help any? We realize that it is not in Matlab but I think you should be able to find those morphological type operators somewhere in Matlab.

STeven.
Thanks Steven, One more favor....
Chandresh Chaudhari from United States  [6 posts]
10 years
Thanks a lot Steven,
I will try to repeat the same performance in Matlab and let you know the results. I am curious to know about " How and on what platform you did this?". If possible please give some more details about the techniques and code that you used.

One more thing I would like to discuss is that it seems that you used something similar to template matching technique. I am more interested in identifying square/rectangle using some geometrical features and make the process free from comparing image with standard template...I have some thoughts for this using signal processing techniques....if you know some related techniques then please let me know...

I seriouslly appreciate this platform that allows images uploading and have better technical discussions.

Have a nice week end.

Thanks,
Chandresh
Square Detection
Anonymous
10 years
Chandresh,

We did the experiments using RoboRealm which is what this forum is about. Have a look at the rest of the site and you'll see the modules we used above.

We didn't use a template matching technique ... but the technique may still fail in many situations. In terms of detecting squares there are several possible techniques. We have one in development that uses lines to define corners which are then used as indicators/beacons to square shape detection. This is primarily a contour based technique. A Hough type system should be also possible but experience with the Hough transforms have indicated that they are somewhat slow.

Have you had any luck with square detection in MatLab?

STeven.
Thanks Steven, I got it using Matlab...
Chandresh Chaudhari from United States  [6 posts]
10 years
Hi Steven,

I asked a questing about square identification in an image and you replied quickly with lot of information. I thank you for that. I got success in my task of recognizing square number plate and cutting numbers from the square using Matlab and am very close to identifying numbers using neural networks and CCF.
I used morpholigical operations and some properties of square object like same length, to detect the square.
I have one question for you, I am not sure that whether this is the right place to ask this question or not? but if it is then...
As I have done MS thesis in robot vision, I am looking for a job in this area, Image processing and computer vision, if you have some idea about potential employers in this field, please reply.
Thanks,
Regards,
Chandresh
Machine Vision Jobs
Anonymous
10 years
Chandresh,

Unfortunately we are not aware of any companies actively looking for machine vision specialists. While we do keep tabs on some potential employee's we (RoboRealm) do not currently have any hiring requirements. Please feel free to post a link here to your resume and/or email us a copy so that we have it on file.

Perhaps we may help you and others find jobs in this field. If you have not already done so check out some of the other commercial companies in this space. I think some of them have job openings on their websites.

See a list at http://filters.sourceforge.net/wikifilters/index.php/LinksCommercialproducts


Good luck!
STeven.
Resume, Chandresh
Chandresh Chaudhari from United States  [6 posts]
10 years
Hi STeven,

Thanks for offering help. Please find the attached resume. Please provide your email id so that I can send you a copy too.

Thanks,

Regards,
Chandresh
Chandresh, Resume
Chandresh Chaudhari from United States  [6 posts]
10 years
Here is my Resume.

-Chandresh
Page 2 Resume
Chandresh Chaudhari from United States  [6 posts]
10 years
Page 2
Ram Hari Regmi from Nepal  [1 posts] 9 years
I have started project of campus as no. plate detection but i am totally new to matlab.
I have only 25 days left for the completion of the project. I am trying to abstract the number plate area from the car but unknown how to do. I have read your discussion and have been impressed. But i am totally new to matlab. Can anyone help me in this topic.
Waiting for ur reply.
Anonymous 9 years
Ram,

As mentioned before we don't specifically know Matlab (just too expensive to purchase) but we might be able to help with a particular technique that Matlab might be able to do (you will have to figure that part out).

What have you though about doing so far to extract out the license plate? Do you have a sample image that you are working on?

STeven.
Ram Hari Regmi from Nepal  [2 posts] 9 years
I should identify and heightlight the no. plate location in following figure so that i can crop that part and use OCR to identify actual no. plate.
Ram Hari Regmi from Nepal  [2 posts] 9 years
How can i implement this algorithm in MATLAB in binary picture.
{
      If number of ‘white’ pixels < 10 ; pixels become ‘black’
         Else ; no change
      If number of ‘white’ pixels > 100 ; pixels become ‘black’
         Else ; no change
}

Anonymous 9 years
Ram,

We're not sure about how to do this or the thresholding in Matlab but in RR you could use the following robofile that produces this image

[image1]

Basically it reduces the colors to create blobs and then eliminates all blobs that are not close to 4.5 aspect ratio. Then the remaining largest object is filled in and masked back onto the original image.

Works for this image ... but most likely is not a general solution but should give you some ideas. Also have a look at

http://sluggish.uni.cc/AVNPR/AVNPR.htm

for some other tips.

Perhaps the mathworks forum is a better place for MatLab discussions?

Good luck!

STeven.
Anonymous 9 years
Opps, here's the image and robofile.

program.robo
Anonymous 9 years
Thanks!

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