Astroart Forum

Every time I load an image it looks really bad. Is there a way to set a range of V 1300:8000 either from a script or as a default when looking at images?

It seems that the default image range is always very small like ... V 1100:1300

Of course this looks just like noise.

Regards,

John

Well I tried to change the FIT header information AVISUMAX and AVISUMIN but they are read only?
But if you change the visualisation to what you want and then save the file, when you read it back it stays with the new visualisation. Very strange as there are no other parameters in the FIT header that could impact Visualisation. I also tried the Camera Control OPTIONS -Visualisation of new images' but as I suspected this is only new camera images.
I need to do some more FIT file format research to find out how the FIT file knows the visualisation without changing the data content (which it does not).

Hello, there is no a standard FITS keyword for visualization. AVISUXXX is key written and read by Astroart.
The options for visualization of new images (downloaded from camera) are inside the Camera Control Options, as you wrote.

Yes, but how does the FIT file remember the visualisation?
There does not seem to be a way to change the visualisation from a macro or script. Except going through say 100 images and loading them changing the sliders at the side and saving them again.
Once manually changed and saved the AVISUMAX and AVISUMIN stay at the new value but I don't seem to be able to write to them?

The visualization is remembered (saved) if the option "Add visualization keywords when save" is enabled in the Preferences, Observer page, FITS section.

By the way, a too stretched visualization can be fixed easily, for example:

A) Pressing F4, then maybe F6 for logarithmic.
B) Clicking the Status Bar of the image ( R = .... B = ... etc).

Or tuned quickly:

A) Pressing PAGE-UP / PAGE-DOWN
B) Rotating the mouse wheel.

If you are making a catalog of reference images for supernova search, then you should decide in advance which kind of visualization will be used, so that it will match the visualization of images download from the camera. A stretched visualization can be very useful.
A script command for visualization mode does not exist, but it could be easily added if requested.

Ok Fabio,

This is the answer!!
"The visualization is remembered (saved) if the option "Add visualization keywords when save" is enabled in the Preferences, Observer page, FITS section."
I have turned it off and now I can change the visualisation from a script!!
I can now write the keywords and save then reload.

Image.Setkey("AVISUMAX",3000.0)
Image.Setkey("AVISUMIN",800.0)
Image.Save("C:\Users\John\Desktop\temp\SAVE\Test.fit")
Image.Close()
Image.Open( "C:\Users\John\Desktop\temp\SAVE\Test.fit")

Just need to read the background and critical star value then do the above.

Thanks,
John