| Re: Three questions [message #11389 is a reply to message #11385] |
Wed, 08 April 1998 00:00   |
biomedical
Messages: 13
Registered: January 1998
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Junior Member |
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David Foster wrote:
>> 1: what is 'sharp' function to images, or 'sharpening'?
>> what is 'unsharp' ? how to do them in IDL?
>
> These are just basic filtering techniques, to enhance either
> low-frequency or high-frequency information in the image.
> You can use convolution (CONVOL) with specialized kernels to
> perform both.
>
Thank you for your help. It seems that low and high frequency filtering
only give low and high freqency components of the image, the result
image doesn't seem sharper. I used butterwidth, hanning, expontential...
maybe you have some special filter. Band pass and reject do not work
for me either. The convolution (convol) seems to give the same image
if the kernel is delta function, otherwise it will give unsharp results.
Could you give me more specific kernel or filter information?
>> 2: how to read 1-bit Tiff (mono) file?
>> 3: how to do the Matlab image processing, please take a look at:
>> http://www.mathworks.com/demos/toolbox/image/ipss0011.html
>> how to removes the minor regions, skeletonize, ...
>
> Get a good book on image processing, and look into Convolution
> (IDL's CONVOL) as a means to do filtering,
> edge detection, feature removal, etc. The BW* Matlab routines
> are very specialized functions, from the Image Processing toolbox
> I would guess; I'm not sure IDL has anything like that. But do
> look into LABEL_REGION, ROBERTS, SOBEL, SEARCH2D, ERODE, DILATE.
>
I know IDL can easily do something, and also can do something else
not that easy. I expected IDL to do this 'skeleton' easy. I found
myself that it is not easy at my level to do this. I hope someone who
has code for this and is willing to contribute.
BTW, my question is very specific, just do what Matlab did!
you can use their image to test. Finaly you can get just enclosed
lines which segments the region.
> IDL can be used to do what the slide show does, but will require
> some coding. When you get a better idea of what you need, ask
> the newsgroup again, and be more specific. I'm sure someone has
> coded some of these tasks.
>
> Dave
>
>>
>> Thanks, please do NOT send me emails, just post here.
>>
>> Chester
>
> --
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
> David S. Foster Univ. of California, San Diego
> Programmer/Analyst Brain Image Analysis Laboratory
> foster@bial1.ucsd.edu Department of Psychiatry
> (619) 622-5892 8950 Via La Jolla Drive, Suite 2240
> La Jolla, CA 92037
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
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