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Re: jpegs and tiffs [message #57819 is a reply to message #57792]

Mon, 24 December 2007 18:36

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Josh writes:

> The following program is supposed to write two sine waves, a blue one
> and a black one, to two different files. However, on my system, the
> jpeg ends up with two black sine waves, whereas the tiff (as well as
> the window on the screen) end up with a blue one and a black one as
> desired. Any thoughts? Code is taken from Gumley, but with many
> changes.

Well, I don't think there are *really* two black sine
waves in the JPEG file. I think one of them is very dark
blue and the other is black. But, you are right, it is
not as blue as it is in the TIFF file. I think this is
probably because of the "lossy" nature of JPEG files.
I would try setting the QUALITY keyword on the WRITE_JPEG
command to 100 and see if that doesn't help some.

In any case, if you choose a RED color, you will see that
you are getting differences in your two lines. :-)

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: jpegs and tiffs By: David Fanning on Thu, 27 December 2007 13:08
		Re: jpegs and tiffs By: Josh on Thu, 27 December 2007 13:00
		Re: jpegs and tiffs By: David Fanning on Mon, 24 December 2007 18:36

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