[question] rendered image does not have mask as defined via LEL

[kswang1029]

Describe the bug
This is an issue from CARTAvis/carta-frontend#2220 and investigated by @crocka . If the frontend sends the LEL expression “dice_one.fits”[“dice_one.fits”>2], a mask will be generated and applied but the rendered image appears not having the mask. The region statistics, however, does consider the mask.

To Reproduce
Steps to reproduce the behavior:

1. need a modified frontend to disable incorrect parsing of [ ] in LEL expression
2. load an image with LEL like “dice_one.fits”[“dice_one.fits”>2] (see frontend issue Image arithmetic does not seem to work carta-frontend#2220)
3. the rendered image should have a mask but it does not

Expected behavior
The rendered image should have a mask (as NaN)

Platform info (please complete the following information):

• OS [e.g. macOS Monterey]: macOS Ventura
• Browser [e.g. chrome, safari, electron app]: chrome
• Browser version [e.g. 22]: 104
• Backend branch [e.g. dev, v3b2 release]: dev
• Frontend branch [e.g. dev, v3b2 release]: dev