blending and transparency

I would like to create an bitmap image sequence using a Light Flare for use as an animation in another program, where the image sequence would be shown over a background image drawn on a surface in the other program. I can only key a specific color (lime / RGB 0,255,0 would be preferable) as the transparency color for the image sequence. In Hitfilm, I have the Light Flare on the top plane and a lime transparency plane below it.

My question is, which combination of blend mode settings do I need to use on the plane(s) and/or the Light Flare object so that the flare does not blend with the lime transparency color (i.e. turning pixels to RGB 0,255,3 for example)?

Comments

  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff
    edited October 2014

    Light flares are largely transparent, which means you can't stop them blending with the background color. You need to either use a black background, which you can easily remove with a blend mode later on ( the most common technique for flares) or use no background, and export to PNGs with embedded alpha channels.

  • Thanks for the quick feedback.

    I discovered that it is necessary to put the light flare on a grade layer rather than a plane layer in order to get the alpha channel below 255. When exporting, set Codec to PNG and Color depth to 32-bit (RGBA). Now I just need to get the .NET application to use the alpha channel...