[ome-users] ROI Colours: unexpected behavious with null alpha channel

[Mark Carroll]

On 01/20/2016 05:09 PM, Paul Kibet Korir wrote:

> If I set the fill colour of an ROI to rint(0) I get solid black instead
> of nothing (100% transparent black).

That's a surprise to me. I can however confirm it for the latest
versions of both Insight and Web.

> This appears the same as -16777216,
> which I believe is black with full alpha channel (100% opaque or RGBA =
> #000000ff).

That makes sense to me.

(snip)
> Is this correct? Please correct me if I'm wrong.

I have filed a ticket to have us look into this:
http://trac.openmicroscopy.org/ome/ticket/13146. It certainly doesn't
agree with the OME-XML schema documentation I pointed you to previously.

In the meantime, if I set the alpha channel to just 01 instead of 00, so
very nearly transparent, then both Insight and Web behave as we'd
expect. Perhaps that workaround may suffice for now?

-- Mark

The University of Dundee is a registered Scottish Charity, No: SC015096