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Re: Reading 256x256x16bit images [message #6377]

Wed, 19 June 1996 00:00

peter
Messages: 80
Registered: February 1994

Member

Jason Young (jyoung@olie.wvitcoe.wvnet.edu) wrote:
: This sounds like something I tried to do about a month ago. Except
: mine were 512x512x12bit CT scan images. Of course the relative intensities
: sould have been 0 to 4095 so the code looked like this:

: a=intarr(512,512)
: a=ishft(a,-4)
: tvscl, a

: This could create an image, but for some reason there was alot of
: noise around where the bone should have been. I have tried many different
: scaleing procedures that haven't helped. I also noticed that the data is
: chopped because the upper value is 4080. This would probably be the cause
: of the upper end noise since dence bone should be above 4080. I had to do
: the shift because of IDL being 16 bit.

Scaling by bit-shifting shouldn't make any difference, since tvscl does
the scaling anyway. How big are the files? Is each 12-bit pixel stored
in a 16-bit word on disk? Or are two 12-bit pixels stored in 3 8-bit
bytes? If the latter, you'll have to do some fancy bit-twiddling to
correctly load the image.

Finally, are you sure you don't need to byteswap the data?

Peter

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[Message index]

		Re: Reading 256x256x16bit images By: peter on Wed, 19 June 1996 00:00
		Re: Reading 256x256x16bit images By: jyoung on Wed, 19 June 1996 00:00
		Re: Reading 256x256x16bit images By: jsbenens on Sun, 16 June 1996 00:00

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