Describe the bug
from CARTAvis/carta#226

The HIPASS survey produce FITS cube like

where a BLANK keyword is defined.

Current CARTA does not handle this so those pixels considered as BLANK are with a value about -8 in the case above.

To Reproduce
Steps to reproduce the behavior:

1. load https://drive.google.com/file/d/1lP1RrozgP-vpjyRDOQNuWMWNOPFC-Vqz/view?usp=share_link
2. see the image with pixel value -8 in the area supposed to be BLANK (ie NaN)

Expected behavior
Check for BLANK header and apply masking (set to NaN)

Platform info (please complete the following information):

• OS [e.g. macOS Monterey]: Sequoia
• Browser [e.g. chrome, safari, electron app]: chrome
• Browser version [e.g. 22]:
• Backend branch [e.g. dev, v3b2 release]: dev, v5, v4.1
• Frontend branch [e.g. dev, v3b2 release]: dev, v5, v4.1