ridge finder algorithm?

[Bill Christens-Barry]

Can anyone point me to an algorithm for detecting ridges in a monochrome image? I'd like to end up
with a binary image comprised of single-pixel width lines along the ridges. I can think of several
ways to do it, mostly involving looping over a range of thresholdis, but these methods seem very
inefficient.

Thanks.

Bill Christens-Barry

[Kenneth Sloan-2]

First, you need to find edges...and then cull isolated edges that  
don't link together into longer ridge-like features.

The first hit on Googling "ridge finding image" led me to John Russ's  
very good "Image Processing Handbook".

I would start there.


On May 18, 2009, at 6:48 PM, Bill Christens-Barry wrote:

> Can anyone point me to an algorithm for detecting ridges in a  
> monochrome image? I'd like to end up
> with a binary image comprised of single-pixel width lines along the  
> ridges. I can think of several
> ways to do it, mostly involving looping over a range of  
> thresholdis, but these methods seem very
> inefficient.
>
> Thanks.
>
> Bill Christens-Barry

--
Kenneth Sloan
[hidden email]

[Michael Schmid]

Hi Bill,

you could also search the literature for medial axis transform; some  
of these methods work by searching for ridges in the EDM.

For a very simple algorithm, have a look at the trueEdmHeight method  
of the ImageJ built-in MaximumFinder
   http://rsb.info.nih.gov/ij/source/ij/plugin/filter/MaximumFinder.java
Remove all the height calculation, just set a pixel in the output if  
a ridge or maximum has been found.
If required, you could then run "skeletonize".
The disadvantage: there is no noise tolerance, so it would be  
unsuited for, e.g., a medial axis transform.

Michael
________________________________________________________________

On 19 May 2009, at 02:33, Kenneth Sloan wrote:

> First, you need to find edges...and then cull isolated edges that  
> don't link together into longer ridge-like features.
>
> The first hit on Googling "ridge finding image" led me to John  
> Russ's very good "Image Processing Handbook".
>
> I would start there.
>
>
> On May 18, 2009, at 6:48 PM, Bill Christens-Barry wrote:
>
>> Can anyone point me to an algorithm for detecting ridges in a  
>> monochrome image? I'd like to end up
>> with a binary image comprised of single-pixel width lines along  
>> the ridges. I can think of several
>> ways to do it, mostly involving looping over a range of  
>> thresholdis, but these methods seem very
>> inefficient.
>>
>> Thanks.
>>
>> Bill Christens-Barry
>
> --
> Kenneth Sloan
> [hidden email]