The ATEM switcher doesn't work with PNG images that have transparency. Bad decision by BMD if you ask me as it's the default for transparancy on the web. They should just support importing transparent PNGs and convert them on the fly.
In order to get transparancy to work on an ATEM switcher you need an image with an premultiplied key. This is what the BMD Photoshop plugin creates for you when you export to the ATEM directly. There are two videos by PhotoJoseph on YouTube (
,
) that clearly explain the difference and shows you how to create an image with a premultiplied key manually.
For Photoshop the steps are:
1. Load the image with transparency into Photoshop.
2. Duplicate the layer
3. Create a new layer at the bottom and fill that entirely with a black color.
4. Select the bottom two layers (the transparent image and black fill layer) and press Ctrl-E (or Cmd-E on Mac).
5. Hold the Ctrl (Cmd on Mac) while clicking the thumbnail of the original layer with transparancy.
6. Select the newly created merged layer and from the menu select Layer -> Layer Mask -> Reveal Selection
7. Delete the layer with the original transparent image.
8. Save the image to a PNG with transparancy.
9 Load that image into the ATEM and make sure to enable the Pre Multiplied Key checkbox in the keyer.
PS: For some cases where you don't need semi transparency (e.g. shadows, gradients) a simple transparent PNG will work just fine as the black added in the above steps will not be visible.