[ITK-users] Location of 4-connected voxels with a specific intensity

[Bradley Lowekamp]

Hello,

Yes the gray scale morphology filers will work fined with signed, unsigned or real pixel types.

The quote you are referring to is describing the structuring element, not how the structuring element is applied. Essentially the structuring element is a binary image.

Brad

On May 20, 2014, at 10:20 AM, Mirco Serra <mirco9091 at hotmail.it> wrote:

> Hi Bradley,
> 
> sorry to bother you again. Would the method that you suggested work also for DICOM images with values ranging from -1024 to 0? I got this doubt because reading the description of the GrayScaleDilateImageFilter it reads "Only elements of the structuring element having values > 0 are candidates for affecting the center pixel." So, I suppose that in this case I should use a different dilate filter instead?
> 
> Thank you very much!
> Mirco
> 
> From: mirco9091 at hotmail.it
> To: blowekamp at mail.nih.gov
> Date: Thu, 15 May 2014 17:42:35 +0000
> CC: insight-users at itk.org
> Subject: Re: [ITK-users] Location of 4-connected voxels with a specific intensity
> 
> Great, thank you very much indeed!!
> 
> Subject: Re: [ITK-users] Location of 4-connected voxels with a specific intensity
> From: blowekamp at mail.nih.gov
> Date: Thu, 15 May 2014 13:25:19 -0400
> CC: insight-users at itk.org
> To: mirco9091 at hotmail.it
> 
> Hello,
> 
> I am suggesting using a cross structuring element, which has the same topology as the 4-connected neighborhood. The output of gray scale dilation is the maximum value of the pixels contained in the structuring element at a location. There are plenty of textbooks and website which provide a more in depth description of grayscale morphology if you need further information.
> 
> SimpleITK's python binding may be a good tool to interactively explore how to combine some of these filters to get your desired results.
> 
> 
> Hope that helps,
> Brad
> 
> On May 15, 2014, at 1:15 PM, Mirco Serra <mirco9091 at hotmail.it> wrote:
> 
> Hello Bradley,
> thanks again for your help. Just to make sure, you are suggesting I use use the itkGrayScaleDilateImageFilter with a binary ball structuring element of radius 1 followed by a itkThresholdImageFilter. Is that correct? How is the dilation helping find the 4-connected voxels that share the intensity property?
> 
> Many many thanks,
> Mirco
> Subject: Re: [ITK-users] Location of 4-connected voxels with a specific intensity
> From: blowekamp at mail.nih.gov
> Date: Thu, 15 May 2014 11:49:32 -0400
> CC: insight-users at itk.org
> To: mirco9091 at hotmail.it
> 
> Hello,
> 
> I think a Grayscale dilate and then a threshold may do what you want, if you use a cross with a radius one. The dilate with take the maximum over this template.
> 
> Hope that helps.
> Brad
> 
> On May 15, 2014, at 11:45 AM, Mirco Serra <mirco9091 at hotmail.it> wrote:
> 
> Hi guys,
> 
> I have a 2D gray-scale image and I need to locate all the sets of 4-connected voxels that have an intensity below a certain threshold. Do you know which method may be the best in order to do so?
> 
> Many thanks in advance for your help,
> Mirco
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