Image on top of video

ChristerTX wrote on 11/29/2003, 10:05 PM

This is similar to my other post but another thought.
Can I make put a smaller picture on top of a video event with the picture appearing to float on the video event ?

What I'm looking for is to have a similar effect as the text with transparent background but with the difference that it would be an image instead?
An example would be a coca cola logo floating across the screen.

Can I do that in ScreenBlast or can I buy add ons that accomplish this?

Comments

JohnnyRoy wrote on 11/30/2003, 7:58 AM

Also answered in your other thread. You need to use another program to process your image and give it an alpha channel so Screenblast will know what to make transparent. Think of it this way, you have 4 channels, Red, Green, Blue, and Alpha. Using the first three you can create any solid color. Using the fourth (alpha channel) you can control the transparency. You will need an image editing program to do this. One that I find very useful for this is Paint Shop Pro 8 because it has a background eraser tool that will allow you to manually erase the part of the background you don’t want. Then export it as a PNG file with transparency set to the alpha channel and Screenblast will show your image correctly.

You can download a trial copy of Paint Shop Pro 8 from Jasc Software. You could also use something like Adobe Photoshop or any other image editor that supports alpha channels.

~jr

Monsta wrote on 12/1/2003, 2:14 AM

After you get the image transparent how do you set the image as an alpha channel?

JohnnyRoy wrote on 12/1/2003, 4:32 AM

I’m not sure if you're asking how to set the alpha channel in your image editor or how you get Screenblast to acknowledge an alpha channel that’s already there?

To force Screenblast to see the alpha channel:

Step 1: Place the image on an Overlay or Text track and if the alpha channel isn’t recognized...
Step 2: Right-click on it and select Properties from the context menu.
Step 3: On the General tab of the Video Event Properties dialog that pops up, press the Media Properties button on the top right of the dialog.
Step 4: From the Properties dialog, go down to the last property labeled Alpha channel: and select Straight (unmatted) or one of the Premultiplied settings.

This should activate the alpha channel and your Video track should now show through the transparent areas.

Creating the alpha channel for your image in the first place is dependant on what application you’re using as an image editor.

To make an alpha channel in Paint Shop Pro 8:

Step 1: Use the Background Eraser tool to remove your unwanted background (this leaves the area transparent).
Step 2: Use the Magic Wand selection tool to select the area that is now transparent.
Step 3: Use the menu item Selections->Load/Save Selections->Save Selection to Alpha Channel and just press Enter to accept the alpha channel in the next dialog box.
Step 4: Use the menu item File->Export->PNG Optimizer select the Transparency tab and make sure Alpha channel transparency is selected.
Step 5: Push the OK button and give your file a name.

The procedure will be similar for other image editors (although the menus will be different).

~jr

Steve Grisetti wrote on 12/1/2003, 6:21 AM

You can also use the chromakey feature, as JohnnyRoy described in your earlier post, with your floating image on the video track above the background.

If you're goal is to do a picture-in-picture effect (which can even be done with live video) you can put the video that you want to "float" on a layer above your background and then use pan & crop on your floating video, stretching the frame way beyond the edges of the video so that it appears smaller with your background revealed around it. (You can also use pan & crop to position where your floating image appears on the screen.)

ChristerTX wrote on 12/1/2003, 6:37 AM

Thanks,
I used Adobe Photoshop and it worked great. Saved the image in PNG format.
I did not have to do anything in the Screenblast program to get this working. When dropped the image in the Video Overlay track, it had the gray and white squares in the background indicating that it was transparent.

Thanks for your help !