alexandra Verhaest

I've got a still image which I want to trigger to appear on top of a video layer. I'm a bit at a loss as to how to do this as processor-friendly as possible.. as for now, I have tried using jit.alphablend and rendered my still as a .mov with an alpha channel.. but nothing happens. I am quite the n00b... so I guess there is an obvious simple processorfriendly way to do this... can anyone point me into the right direction?

still-image-with-alpha-over-video

You can find some antiquated-but-still-essentially-correct examples on this page:

Scroll almost all the way down, to the patches labeled "make a mask image", "mask by multiplication", and "mask by alphablend". See also Jitter Tutorial 29: Using the Alpha Channel.

The same effects can be achieved in GL with more efficiency, but if you're new to Jitter I recommend the above methods first (which it seems you're already attempting).

You can find some antiquated-but-still-essentially-correct examples on this page:Programming Examples
Scroll almost all the way down, to the patches labeled "make a mask image", "mask by multiplication", and "mask by alphablend". See also Jitter Tutorial 29: Using the Alpha Channel.

The same effects can be achieved in GL with more efficiency, but if you're new to Jitter I recommend the above methods first (which it seems you're already attempting).


you don't need to render your image as a .mov, as jit.qt.movie loades image files (PNG, which supports alpha, is your choice).

I have used the alphablend-patch from the mask-tab of it's helpfile for now. Below is the relevant part of my patch. I'll give png a try indeed.. but would this be the most lightweight solution to my problem? The image that needs to be masked upon the main movie is actually tiny.. about 10x10 pixels.. Is there a way to map a smaller image with alpha onto a bigger one and use coordinates to get it in the right place?

Hi there!
Thanks for the replies!
I have used the alphablend-patch from the mask-tab of it's helpfile for now. Below is the relevant part of my patch. I'll give png a try indeed.. but would this be the most lightweight solution to my problem? The image that needs to be masked upon the main movie is actually tiny.. about 10x10 pixels.. Is there a way to map a smaller image with alpha onto a bigger one and use coordinates to get it in the right place?

still image with alpha over video