Cell detection only partially supports fluorescence images

[petebankhead]

The primary cell detection command under Analyze → Cell analysis → Cell detection is primarily intended for brightfield images.

However, it ought also to work for fluorescence. Under some conditions it does, namely when:

• the first fluorescence channel contains a nuclear staining (e.g. DAPI)
• the Max background intensity parameter is either set negative or very high, or Background radius is negative
• the Threshold value is set appropriately high

This is because, in the case of fluorescence data, the command only looks for the first available channel within which to detect nuclei. Furthermore, the Max background intensity and Threshold parameters, by default, are selected for optical density units... which can be far away from being sensible values for fluorescence.

The command should be adapted to use more sensible defaults in the case of fluorescence images, and to permit the selection of alternative channels.

[petebankhead]

This will be addressed in v0.0.5