| adjustimg brightness of an image [message #13150] |
Sat, 17 October 1998 00:00  |
akk
Messages: 10
Registered: July 1998
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Junior Member |
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Hi,
I am writing a program which scales images(i.e. images of galaxies) ,
adjusts their brightness and apparent distances, and then adds each image
to a final image, which in the end just comprises all of the images which
were added to it.
Many of the images on the final image appear very faint, and I was told
that
one can use the tvscl command to adjust brightness by using the following
syntax:
tvscl<Number1>Number2
To my understanding this will make all pixels with values LESS
than Number1, equal to Number1 and make all pixels w/ values GREATER than
Number2
equal to Number2, while adjusting all other pixels with values in between
Number1 and Number 2 accordingly.
I've tried using the tvscl keyword ( with varying values of Number1 and
Number2) but after the image is redisplayed, only a black screen appears
(with no apparent image on it). I've tried adjusting the brightness
of other already existing images, and also have had no luck.
In addition I tried making Number1 = MIN(finalimage), and Number2 =
MAX(finalimage), thinking that the final image would be redisplayed
as if i had just entered in "tvscl, finalimage". However a only blank
image is redisplayed to the screen.
I've looked through the IDL userguide books, ONLINE Help, and various web
pages, but haven't seen any information on using tvscl in this different
format (tvscl<...>...).
Does someone know another way of adjusting the brightness of an image, a
web site where this format of tvscl is explained, or
could someone tell me if I am misunderstanding the use of tvscl<..>..?
In addition when viewing my final image with "tvscl, finalimage"
the foloowing error was outputted:
Program caused arithmetic error: Floating illegal operand
How can I correct this error?
Thanks, in advance...
Anil
p.s.: Please respond to my email address
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