Using alpha channels with A.M.

[raineyeric]

Hi,

I am trying to render an image that looks like fairy dust emitting from a simple ball object. I used a sprite and when I render the image(with alpha) it looks great. Fairy dust is emitting off of the object and it looks like a comet. But it only looks good when I look at it in quicktime. When I bring it into programs like an AVID or final cut all I can see is the object and not the sprites. I need to render it with the alpha because I want to use this comet as a transition between shots(a lot of shots). I am posting two images. One image is what I want it to look like the other is what the exact same image looks like in an editing program.

 

Any help would be great!

 

Eric

[Bruce Del Porte]

The bottom looks like the sprite to me, just on a smaller scale. What does the bottom image look like against a dark background in Avid/FC.

[johnl3d]

Just a thought when I have used the alpha channel I usually use no compression settings otherwise I've gotten mixed results. Was your quicktime compressed?

Or do it as a targa series and use that in post. My humble experience ....with AM

[raineyeric]

I did render it as a targa. I thought the same thing might be true but I get the same result. No sprite with alpha channel.

[mtpeak2]

Is the background color of both sprite images used in the emitter the same color?

[raineyeric]

The images are the exact same..... The top image is what it looks like when it is opened in quicktime. The Quicktime program I don't think knows how to deal with alpha channels like a program like Avid, Final Cut, Photoshop. The bottom image is the exact same image but it is opened in one of those programs. All that is showing up is the sprites that cover the original ball "object". I can't believe no body has delt with this problem....

 

eric

[mtpeak2]

Can you post the images that was in the sprite emitter? And what camera background color did you have set when you rendered in A:M?

[John Bigboote]

Yes- Hash gets fussy with sprites and alphas, glows as well do not appear in the alpha. But here is a quick Photoshop workaround:

 

Open a middle frame One typical of the imagery, say frame 78...)in Photoshop. Find the 'actions' window and choose New action, name it and 'start recording'. This will automate the process you do on 1 frame to ALL the frames.

 

Now Photoshop is 'recording' what you do:

 

Choose 'All', Copy. Go to channels, click on the 'bad' hash alpha channel and Paste. You know have a workable alpha, tweak it with the Brightness and Contrast effector.

 

In Actions window, hit 'stop recording'.

 

Close the frame WITHOUT saving. Now, under file, find Automate-Batch. Your action will be the default, so leave that, simply find the folder where all your .tga's are and choose 'save and close'. Now hit okay and stand back and watch as Photoshop does your wishes to ALL the frames in the folder.

 

NOW open the sequence in After-Effects, AVID or Premiere and say 'Thanks to the guy on the hash Forum!

 

DAMN! I'm good!

 

BTW- your sprite looks really cool!

 

ATTACHED- Example of the action as I did to your file in 10 sec in Photoshop...

[raineyeric]

John,

 

You are the man!!!!!!!!! i am going to try the photoshop work around...but i thank you for helping me!

[pia12254]

I really like the Photoshop workaround...very cool! I have used Actions and Automate Batch a few times and it can be a lifesaver for multitudes of seperate pictures or pic sequences...

 

The suggestion I was going to make is maybe try a simple Luma Key and have it key out darker. It seems to work pretty well for that type of thing.

 

Just another thought. Hope you got it working!

[John Bigboote]

 

The suggestion I was going to make is maybe try a simple Luma Key and have it key out darker. It seems to work pretty well for that type of thing.

 

Basicly, my photoshop 'work-around' with actions IS a luma-key.

 

It is taking the image and converting it to 256 levels of black to white, so any pixel with a color value will translate to a grey rather than black and will be represented in the alpha by its luminence value.

 

If you wanted to use a 'keyer' filter in Premiere or After Effects it would work similiarly, but frequently an unwanted 'ring' around the effect is a by-product.

 

Any work I can do in Photoshop is preferrable to working in AE or Premiere. Remember, Photoshop is an image manipulation and photo-retouching APP, whereas the others are video based. I see this most via 'scaling'. Take an image and scale it down say, 33% in both apps and compare...Photoshop does a better job.

[MATrickz]

Wow, well I dont really have anything else to say except that the sprites look great! I really like the look and I think you did a great job!