Visualizing Masks

Integer valued masks can be used to select out regions of the displayed image for inspection. These must be four byte integers (not shorts) and have the same dimensions as the viewed image. Such masks are produced by the CUPID and SExtractor/EXTRACTOR packages.

Using this toolbox is straight-forward, just identify the mask data file and press Apply. That will extract all regions that have positive non-zero values associated with them in the mask. To select a specific mask value either enter the value in the Values field and press Apply, or move to that value in the Value slider.

To select a range of values enter these in the Values field using. These can be given as individual values like:

      1 2 3 10 11 12

or as ranges:

      1-3 10-12

To get the unmasked image back just close the toolbox or press the Reset button.

To invert the mask, i.e. see all the parts of the image not masked by an integer, just select the Invert: control and press Apply. Note that some masks offer this not-masked facility using the value 0 instead of BAD.