Hello group,

I have two questions:

1. If I use the command "Process -> File Math -> Divide By"
to divide image A by image B, then the result is
not correct, but always scaled. To get the unscaled result I have to measure a background area of image A, image B and result image C. Then I can calculate a factor to get the real result for the operation A/B.
Is it possible to do a file divison without rescaling?

2. Batch Processing:
Is there a possibility for batch processing or
is this feature planned for future releases of CCDSTACK?

e.g: A part of my workflow is always the same:
There are 4 images as input. With these 4 input images I use several commands (Combine->Maximum, FileMath, PixelMath, save as)

I could do these processing steps in a batch job with the freeware IRIS. But Iris uses only 16bit.
So, it would be wonderful, if this possibility
would also be available inside CCDSTACK.

best,
Bernhard

Or how about a recording feature that you could save the steps and recall later?

Larry

quote:

1. If I use the command "Process -> File Math -> Divide By" to divide image A by image B, then the result is not correct...

For File Math division (not pixel math) the divisor image is normalized to avg ADU = 1.0 prior to division (same as flat fielding). This is usually more desirable than a simple division. If you want unmodified division then multiply the result by the avg ADU of the divisor image (via pixel math).

I could add an option to omit the normalization. What are you doing that requires simple division?

quote:

2. Batch Processing:
Is there a possibility for batch processing or is this feature planned for future releases of CCDSTACK?

I am working on that issue . Interestingly, not long after CCDStack was introduced I did a survey of users and one of the questions asked if batch/script processing was a desirable feature. Almost no one was interested in batch processing and so it was put on the back-burner. But lately there have been several requests for it.

Stan

Thank you very much, Stan!

quote:

I could add an option to omit the normalization. What are you doing that requires simple division?

That would be fine for the next release.
Peter Riepe and Harald Tomsik have published a nice
algorithm for better preserving of star colors during nonlinear
stretching of an RGB image. This algorithm is called NOLIGCRA (Non linear gradation colour retrieval algortihm). At the moment, I make several tests and I think that this procedure is quite interesting. One of the steps need a simple division.

Batch processing:
Wonderful news! I am very interested in such a feature.
Before CCDSTACK I have been working with IRIS. The command
line possibility is for me a very big plus for IRIS.

best,
Bernhard