# SourceDetectionTask can corrupt image

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## Details

• Type: Bug
• Status: To Do
• Resolution: Unresolved
• Fix Version/s: None
• Component/s:
• Labels:
• Team:

## Description

SourceDetectionTask can silently corrupt the provided exposure by fitting and subtracting an invalid background model that that results in the image being all nans. I believe the task should realize that the background model is invalid and raise an exception in this situation.

I first saw the problem with an image that had several hundred counts of background. Detection detected a single source and the results were as described. I have attached code demonstrating the issue. Setup meas_algorithms and run showBackgroundBug.py to see the problem.

## Attachments

1. postIsr.fits
19.45 MB
2. showBackgroundBug.py
2 kB

## Activity

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Paul Price added a comment -

This commonly happens when there are NANs in the image: they get into the background model, and from there to the background image, and then into the background-subtracted image.

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Paul Price added a comment - This commonly happens when there are NANs in the image: they get into the background model, and from there to the background image, and then into the background-subtracted image.
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Russell Owen added a comment -

Paul Price the input image has no nans (at least in the image plane; I have not checked the variance plane). But if that is also a known failure mode then it sounds worth testing for it. I do believe that the background model has nans, and I think that should raise an exception.

Show
Russell Owen added a comment - Paul Price the input image has no nans (at least in the image plane; I have not checked the variance plane). But if that is also a known failure mode then it sounds worth testing for it. I do believe that the background model has nans, and I think that should raise an exception.

## People

• Assignee:
Unassigned
Reporter:
Russell Owen
Watchers:
Jim Bosch, John Swinbank, Paul Price, Russell Owen
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Watchers:
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## Dates

• Created:
Updated: