Offline macOS app (distributed as a .dmg) or Web App for creating pixel masks on FITS images. Paint mask regions, preview the masked .fits file, and export FITS or DS9 region files. The app can also be used as a .fits image viewer.

The app can be downloaded simply by clicking on the following button:

One can also use the Web-version by cloning the repository and launching Masking.html

• Load FITS images (.fits, .fit) via local file input.
• Mask IN/OUT modes with brush and eraser, adjustable radius.
• Choose the size of the circular brush and mask the .fits file.
• Display scaling (linear, log, sqrt, asinh, power) and colormaps.
• Pixel magnifier inspector.
• Auto stretch by percentile and ZScale.
• Export mask FITS, masked FITS, and DS9 .reg files.

1. Download the .dmg file.
2. Open it and drag the app into your Applications folder.
3. Launch the app and load a .fits or .fit file.

If macOS shows the message: "FITSme” Not Opened; Apple could not verify “FITSme” is free of malware that may harm your Mac or compromise your privacy, this is normal for apps that are not distributed via the App Store.

To open the app anyway:

1. Open Settings
2. Go to Privacy & Security
3. Scroll down to the Security section
4. Click Open Anyway next to the app

You only need to do this once. After that, the app will open normally.

• Mask OUT: painted regions are rejected (mask value 0).
• Mask IN: painted regions are kept.
• "Apply Mask" toggles between overlay view and masked rendering.

• *.fits mask (binary mask).
• *_masked.fits (fits file with mask applied).
• *.reg DS9 region file.