garageCube

[brain]

hi there,

this sounds so simple, but i have not yet found the best way to create a round mask. yes, i have created a huge black PNG whith a round hole, and this works.

but it would be much more convinient to have a circle black shape with transparency around it; and invert this mask.

any ideas on that? how to invert the alpha channel on a single layer?

[mowgli_uk]

what's wrong with the png you've created if it does the job?
you can't invert non-existent pixels.

[brain]

if i use a big solid PNG with a transparent hole, there is a limitatiion to scaling and rotation, because at some point the edges of the PNG will be visible.

so it would be more clever to have just a circle shape with transparent suroundings just show whats inside.

[mowgli_uk]

just make the png with a bigger space around it, being a still it won't take much cpu.
alternatively make a png or jpg with black and white rather than using an alpha channel and then use the luma key accordingly

[moonbase]

Agree with mowgli, make it really big, keep experimenting to find a size that suits.

I made a round mask for a cd launch show which took place in a cinema near me and used it
as a spotlight for the 'tween number announcements, see here:
http://moongold.me.uk/gig/
first clip, about 35 secs in.

Worked a treat. It was 5000 x 3000 if I remember and very small in kb, can't find it
at the mo but a few 100 kb no more. Colour change on auto, movement, great.