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stpjhj |
02/19/2018 06:12AM (Read 1706 times)
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Status: offline
Registered: 07/09/2014
Posts: 3
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Hi!
When I use IRAF, I use ds9 to check images. I do this in following ways
PHP Formatted Code
cl > !ds9 &
cl > display whatever .fits
But, ds9 shows the values of pixels on which mouse is hovering, and the value is different from original ones.
For instance, if I open a fits image of 16-bit integers by invoking display command, pixel values become floating points, which are close to the original value, but not identical.
Does anyone know how did this happen, and what can I do to see the image as is?
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fitz |
02/19/2018 01:31PM
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Status: offline
Registered: 09/30/2005
Posts: 4040
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The DISPLAY command must scale the image from the original dynamic range of the pixels to the 200 levels used in the display. What you're seeing is an approximation of the pixel value based on that scaling.
When using DS9 you can load the image directly to see the actual pixel values from the file, e.g.
cl\$this->_split2($m[0]) !ds9 whatever.fits
Alternatively, you could use XImtool as the display, or the 'z' command in IMEXAMINE will print a 10x10 grid of pixel values around the cursor position.
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stpjhj |
02/23/2018 09:42AM
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Status: offline
Registered: 07/09/2014
Posts: 3
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I've never used ximtool, but I think I should give it a try.
Thank you.
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