Dark Blooms & Star Cores

[llpastro]

When I open a raw FITS image created by Maxim and if it has blooms or saturated star cores, they are black.  See the attached screen shot.  If I open these images in other processing software, they appear normal.  If I open them in Maxim and resave as a floating point and reopen in PI, they then appear normal.

What do I need to do when downloading images from the camera using Maxim to get these to display correctly?

If I don't worry about their initial appearance and go ahead and calibrate and create masters, will they be correct?

Larry

[Juan Conejero]

This happens because the images have been saved in 16-bit signed integer format, which is wrong. Please save raw data as unsigned 16-bit images.

Alternatively, you can enable the signed integer images store physical pixel data option in FITS Preferences. The same option can be specified as the "signed-is-physical" input format hint in tools that accept them, such as ImageCalibration.

[llpastro]

The FITS header for this image says "BITPIX = 16 /8 unsigned int, 16 & 32 int, -32 & -64 real".  What is this telling me?

Larry

[Juan Conejero]

This is telling you nothing, basically. It's just a generic keyword comment.

You know your image is in 16-bit signed format if BITPIX=16 and you don't have BZERO=32768.

[llpastro]

Attached is the Maxim Dialog box for saving images from the camera.  I thought this was the correct setting, but this setting is causing the issues with the saturated blooms and star cores.  Are there other settings I need to make in Maxim to get unsigned integer?

Larry

[Andres.Pozo]

This is one of the many reasons for deprecating FITS 
It is a really bad standard because it is ambiguous and each application interprets it differently.