RECT and line detection

RECT and line detection

Hello,
I want to write a C/C++ program to detect rectangles in a possibly
rotated image.
I think I should first detect lines of the image using hough transform
and then form rectangles. But I could not find a traight forward
source code which gives line segments of an image. Can anybody help
me?
Thanks.

Re: RECT and line detection

On Sep 7, 6:00=A0am, Alireza  wrote:
> Hello,
> I want to write a C/C++ program to detect rectangles in a possibly
> rotated image.
> I think I should first detect lines of the image using hough transform
> and then form rectangles. But I could not find a traight forward
> source code which gives line segments of an image. Can anybody help
> me?
> Thanks.

You might do a web search for "Harris Corner Detect*"
Regards
ImageAnalyst

Re: RECT and line detection

On 7 Set, 11:00, Alireza  wrote:
> Hello,
> I want to write a C/C++ program to detect rectangles in a possibly
> rotated image.
> I think I should first detect lines of the image using hough transform
> and then form rectangles. But I could not find a traight forward
> source code which gives line segments of an image. Can anybody help
> me?
> Thanks.

Hi,

You can do:
1- Segment the foreground from background using a filter (obtaining a
binary image);
2- Flood-fill the rectangle to obtain the object completed filled
3- Detect vertices using a bounding box

Best regards,
Tiago

Re: RECT and line detection

On Sep 9, 11:40=A0am, tiago  wrote:
> On 7 Set, 11:00, Alireza  wrote:
>
> > Hello,
> > I want to write a C/C++ program to detect rectangles in a possibly
> > rotated image.
> > I think I should first detect lines of the image using hough transform
> > and then form rectangles. But I could not find a traight forward
> > source code which gives line segments of an image. Can anybody help
> > me?
> > Thanks.
>
> Hi,
>
> You can do:
> 1- Segment the foreground from background using a filter (obtaining a
> binary image);
> 2- Flood-fill the rectangle to obtain the object completed filled
> 3- Detect vertices using a bounding box
>
> Best regards,
> Tiago

------------------------------------------------
May or may not work depending on the image.  For example, it wouldn't
work to find all the rectangles that are possible in an aerial photo
of a downtown area, such as Manhattan where you can't get solid
rectangles.  For example, how many rectangles are there in a
chessboard?  We all know it's many, many more than 64!  There's
probably hundreds if not thousands.  (Actually since each corner can
be a corner of a rectangle, it's 64*64 / 2 minus the number of null
area rectangles, about 81 of those)  In such cases, there would be
numerous rectangles, most of them overlapping and you couldn't get
such a binary image.  This method would work well for isolated, non
overlapping rectangles.  Unfortunately the original poster didn't give
enough information (as usual) or post an image so we don't know what
he/she's talking about and doesn't seem interested enough to come back
and check answers to his/her question.
Regards,
ImageAnalyst

Re: RECT and line detection

On Sep 9, 8:31=A0pm, ImageAnalyst  wrote:

> Unfortunately the original poster didn't give
> enough information (as usual) or post an image so we don't know what
> he/she's talking about and doesn't seem interested enough to come back
> and check answers to his/her question.
> Regards,
> ImageAnalyst

Worse, the problem is meaningless. There are no 'rectangles' in images
because there are no 'rectangles' in the world. The word 'rectangle'
first has to be defined here even to have a problem to solve. I think
the first course any image processor should take is 'Scientific and
engineering methodology 101'.

illywhacker;