roscpp clear topics node

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Hi,

I'm using image_transport to publish images, and depending on the format, it will publish it to different topics.

So to give a simplified example:

• if format == grayscale, then I want to publish my images on /image/grayscale
• if format == color, then I want to publish my images on /image/color

That works, but if I want to change format on the fly (eg from grayscale to color), I want to "unadvertise" the topic /image/grayscale" so it doesnt show up in the rostopic list anymore.

Is this in any way possible? I tried first deleting my image_transport object and nodehandle object, then creating new objects and advertise the new topic, but the old topic remains in the list of available topics.