The second option seems to do what I want. Thanks for the tip.

es that seems to workAt 21:20 04/08/2001 +0200, you wrote:

>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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