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| Re: CT image without scaling [message #91982 is a reply to message #91981] |
Thu, 24 September 2015 08:59   |
Dete van Eeden
Messages: 32
Registered: July 2015
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Member |
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On Thursday, September 24, 2015 at 5:41:56 PM UTC+2, David Fanning wrote:
> Dete van Eeden writes:
>
>> How can I display a CT image on idl without it being scaled to 0,255?
>
> I'd try:
>
> TV, image
>
> Or, if the data is not in the range 0 to 255 already, scale it yourself
> with BytScl to whatever range you want within the values 0 to 255
> required to put an image on the display.
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
> Sepore ma de ni thue. ("Perhaps thou speakest truth.")
Thank you, the values range from 1000 to -1000 since it is a CT image and it is displayed in hounsfield units
how many greyscale values will tv, image display?
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| Re: CT image without scaling [message #91983 is a reply to message #91982] |
Thu, 24 September 2015 09:00 |
Dete van Eeden
Messages: 32
Registered: July 2015
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Member |
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On Thursday, September 24, 2015 at 5:59:12 PM UTC+2, Dete van Eeden wrote:
> On Thursday, September 24, 2015 at 5:41:56 PM UTC+2, David Fanning wrote:
>> Dete van Eeden writes:
>>
>>> How can I display a CT image on idl without it being scaled to 0,255?
>>
>> I'd try:
>>
>> TV, image
>>
>> Or, if the data is not in the range 0 to 255 already, scale it yourself
>> with BytScl to whatever range you want within the values 0 to 255
>> required to put an image on the display.
>>
>> Cheers,
>>
>> David
>> --
>> David Fanning, Ph.D.
>> Fanning Software Consulting, Inc.
>> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>> Sepore ma de ni thue. ("Perhaps thou speakest truth.")
>
> Thank you, the values range from 1000 to -1000 since it is a CT image and it is displayed in hounsfield units
>
> how many greyscale values will tv, image display?
But How do I display the image in this new rescaled values alain?
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| Re: CT image without scaling [message #91984 is a reply to message #91982] |
Thu, 24 September 2015 09:07 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Dete van Eeden writes:
>
> On Thursday, September 24, 2015 at 5:41:56 PM UTC+2, David Fanning wrote:
>> Dete van Eeden writes:
>>
>>> How can I display a CT image on idl without it being scaled to 0,255?
>>
>> I'd try:
>>
>> TV, image
>>
>> Or, if the data is not in the range 0 to 255 already, scale it yourself
>> with BytScl to whatever range you want within the values 0 to 255
>> required to put an image on the display.
>>
>> Cheers,
>>
>> David
>> --
>> David Fanning, Ph.D.
>> Fanning Software Consulting, Inc.
>> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>> Sepore ma de ni thue. ("Perhaps thou speakest truth.")
>
> Thank you, the values range from 1000 to -1000 since it is a CT image and it is displayed in hounsfield units
>
> how many greyscale values will tv, image display?
All non-true-color images are displayed with values ranging from 0 to
255. Often, with CT and other medical images, you want to "window and
level" the image.
Here are a couple of articles you might find helpful:
http://idlcoyote.com/ip_tips/xstretch.php
http://www.idlcoyote.com/ographics_tips/contrastzoom.html
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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| Re: CT image without scaling [message #91985 is a reply to message #91983] |
Thu, 24 September 2015 09:14 |
lecacheux.alain
Messages: 325
Registered: January 2008
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Senior Member |
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> But How do I display the image in this new rescaled values alain?
The image function in the statement "im = image(your-image_array)" will open a window on your screen. The variable "im" is the corresponding IDL graphics object.
Changing any of its property (like MIN_VALUE) will dynamically change the display. For instance, doing im.MIN_VALUE=-500 will redisplay your image in range [-500,1000], then doing im.MAX_VALUE=500, in range [-500,500].
IDL himself adjusts automatically the 256 available grayscale levels behind the scene.
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