Treatment of masked and non-finite pixel values

Specreduce provides several options for handling images that contain masked or non-finite pixels. These options allow users to decide whether to preserve, modify, or remove invalid data.

The mask treatment option is selected using the mask_treatment argument in class initializers, methods, and functions where applicable. Note that different classes and procedures within Specreduce may support only a subset of these options.

Available Options

  • apply The input image is left unmodified. Any pixel that is non-finite (e.g., NaN or infinity) is marked as masked, and if an existing mask is present, it is combined with the mask derived from non-finite values.

../_images/fig_masking_apply.svg

  • ignore The input image remains unchanged, and any existing mask is discarded. Non-finite values are neither masked nor replaced.

../_images/fig_masking_ignore.svg

  • propagate The image data remains unchanged. However, if any pixel is masked or non-finite, the entire cross-dispersion axis containing that pixel is marked as masked.

../_images/fig_masking_propagate.svg

  • zero_fill All pixels that are masked or non-finite are replaced with 0.0 and the the mask is cleared from the image.

../_images/fig_masking_zero_fill.svg

  • nan_fill Similar to zero_fill, but instead of replacing invalid pixels with 0.0, they are replaced with nan. The mask is then removed from the image.

../_images/fig_masking_nan_fill.svg

  • apply_mask_only The image and its mask are returned as provided. Only the existing mask is applied without incorporating non-finite value checks.

../_images/fig_masking_apply_mask_only.svg

  • apply_nan_only The input image is returned unaltered, but any existing mask is ignored. A new mask is generated solely based on non-finite pixels.

../_images/fig_masking_apply_nan_only.svg