JS9 Demo: masks and opacity
JS9 allows you to set the opacity of all pixels in an image and/or specify a floor opacity to use if the image pixel is less than or equal to a floor value. It also supports three types of image masks, which can be used to assign opacity or overlay colorsx: These color/opacity features are supported by the JS9.SetOpacity() and JS9.MaskImage() public access routines and the Color Controls plugin.

Left demo: Load the opacity mask image, then the Chandra file. Change default to mask in the Color mode menu (3rd column in bottom row of Color plugin), then choose the mask file and change the opacity value to, say, 0.25 or 0.5. Or change mask mode to opacity to assign opacity directly from the mask values. You can also choose floor in the Color mode menu and set the floor opacity and/or the global opacity directly.

Right demo: Load the LSST test file, then click to display extension #2 of that file separately. Note the use of a user-defined static colormap to assign colors to different areas of the extension. Switch back to the test file, then choose overlay in the Color mode menu (3rd column in bottom row of Color plugin), and choose extension #2 as the overlay.


JS9 Demos:

web page configuration: multiple displays: plugins: colors: data analysis: FITS support: not often needed: