MaxIm Images Strange When Applying STF

[kerrywaz1]

Recently I loaded a set of FITS images into PI taken using MaxIm DL. These images were 16-bit FITS files as output by my camera. However, when I applied STF in PI, these images appeared strangely like 8-bit images, almost posterized. Is there some new setting for FITS files or STF that I need to change to get these images to display correctly right out of MaxIm?

Thanks.

[jkmorse]

Kerry,

Welcome to the world of FITS incompatibilities.  I and others have had this problem crop up in the past, in my case exactly as you have, importing MaximDL captures into PI.  Here is what I have written on the topic in the past:

You may be running into some FITS incompatibility issues.  I did a lot of research recently on FITS incompatibilities and this issue has been addressed time and again by PI.  Here is the results of my research into old posts on the subject:

Fixing FITS Incompatibilities
If you experience these types of incompatibilities, try the following until you hit on a solution:

First
•   Open the Format Explorer (access under “View > Explorer Windows”)
•   Double click on “FITS”
•   Make sure the top two boxes are checked
       o   “Write scaling keywords . . .”
       o   “Signed Integer images . . .”

Second
•   Where possible, particularly in the Image Calibration tool for Lights, but also with ImageIntegration when creating Master Darks and Master Bias, add the following to the “input hints” line under “Format Hints”:
       o   lower-range 0 upper-range 65535

Third
•   If the above does not work, insert the following in the “input hints” line:
       o   Signed-is-physical

Stop using input hints AFTER you have successfully saved an image after applying a PI tool; i.e, do not use input hints in ImageIntegration after successfully calibrating Light images in PI with the ImageCalibration tool (after first PI application, images are saved in proper PI format (0,1) and no longer need input hints)

For an excellent explanation of what is happening to cause this problem, check out the following threads from Juan Conejero:

http://pixinsight.com/forum/index.php?topic=3118.msg21348
http://pixinsight.com/forum/index.php?topic=3474,msg23973
http://pixinsight.com/forum/index.php?topic=3800.msg26086

Also, if you as a starter drinking from a fire hose, I have put together a Cribsheet that I share with a number of other PixInsight users that I update regularly.  If you are interested in a copy, just drop me a line at jkmorse57@gmail.com and I will happy to send the latest version to you.

Hope that helps,

Jim

[llpastro]

Jim, what type of things are on your crib sheet?  I might be interested in a copy.

Larry

[kerrywaz1]

Jim,

I went into Format Explorer and made the changes you suggested. However, the file still open with the centers of the stars (highest pixel values) blacked out, as though the values are being truncated to zero (see attached).

I haven't made any changes to MaxIm, so I am a bit a ta loss as to why this behavior is suddenly happening. Any other suggestions on how to fix this?

Thanks.

[jkmorse]

Larry,

Cribsheet is packed full of stuff, including a detailed workflow and details on how to use the various tools.  I have included a pdf of the latest draft, but that leaves off some details due to size limits and doesn't allow you to adjust to your own needs.  If you want a full Word version, just drop me an email at jkmorse57@gmail.com.

Best,

Jim

[jkmorse]

Kerry,

Ok, have seen this before myself and I have no idea why is happens sometimes and not others.  To fix it try two things, and you may need to do both. 

First, go into MaximDL and do a batch convert to change all your lights to 32 bit floating point files (I know, I know, but it works, trust me, especially on cleaning up the black centers of stars). 

Second, when doing imagecalibration, go into the format hints input line (just below the files box) and add the following exactly as I have written it here: lower-range 0 upper-range 65535

That should do it, but I have no idea why.

Let me know if it works,

Best,

Jim

[kerrywaz1]

Converting files to 32-bit IEEE Float seem to work. I also noticed that saving files as 16-bit unsigned TIFF works just as well.

Since PI works with TIFFs, why not just let MaxIm save images in that format rather than struggling with FITS?

[jkmorse]

Only issue with TIFFs is that they are limited to 16 bits so you would need to convert to FITs or .xisf once you get into PI, but you make an excellent point.  Will try out the TIFFs solution myself.

Best,

Jim

[llpastro]

JKMorse, thanks for the crib sheet.  I would like to be on your distribution list for future updates.  What do you need from me to make that possible.

Larry Phillips

[jkmorse]

Larry,

Just drop me an email at jkmorse57@gmail.com so I have your contact details and you are on the list! 

Simple.

Jim