Sometimes “hot pixels”, pixels whose values deviate too much from the rest of the picture, can be found in images. These kind of outliers may be due to background radiation or also be due to the camera and can affect the image processing negatively if not removed.
This module can be used to remove hot pixels as determined by the set criteria. The hot pixels are then replaced by pixels within the normal range with specified type.
Parameters and I/O
| Parameters | Description |
| Adjust outliers | Choose which kind of outliers to deal with |
| → Both | Deal with outliers that are below and above specified multiples of the standard deviation. |
| → Above | Deal with outliers that are above specified multiples of the standard deviation. |
| → Below | Deal with outliers that are below specified multiples of the standard deviation. |
| Adjustment type | Choose how to treat outliers |
| → Neighbour average | Replace outliers with the average of the surrounding pixels |
| → Custom value | Replace outliers with the to the mean value of the complete image |
| → Image mean | Replace outliers with a specified custom value |
| Deviations from mean [in sdevs] | Choose the multiples of standard deviations from mean that are considered to be an outlier. |
| Input | Description |
| Input | Input images with hot pixels |
| Output | Description |
| Output | Output images with modified hot pixels |
| New/Changed Header Values | Description |
| | No header values are being added or changed. |
A discussion of different CCD characteristics including hot pixels can be found here.