At 20:19 3.8.2001 +0100, Owen Brazell <owen@...> wrote:

> is there a way to display a negative RealSky image ? If you
> invert the
>image outside Guide and try and display it all you get is a white square. I
>guess this is due to the algorithem that tries to figure ou the best scale.
>Some nebula images look best with black stars on a white background.

Hi Owen,

I can suggest two ways of showing negative (inverted) DSS/RealSky images.

- the easiest is to switch from 'Normal' to 'Chart' mode via menu :
Display->Background->Chart mode
However this will show ALL inverted, including other Guide objects

- the second posibility is to right-click near corner of the displayed
DSS/RealSky image and note in the window 'Contrast' values. For example
the line at window says 'Contrast 1000 to 11000'. The you click OK to
close the window and hit Shift-F8 to get a dialog window asking for a
file name. Here you will enter the two values - but in inverted order and
separated with comma (to have the higher number first). In my example you
would enter 11000,1000 and click OK. To return to original settings of the
picture repeat the procedure but after Shift-F8 enter the two values in
its original sequence (in my example 1000,11000)

That should do it.
Regards, Jan

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Jan Manek
Stefanik Observatory Private :
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