Posted: Thu, 1st Apr 2010, 8:53pm
Post 1 of 16
Is there any way for me to extract an image from a green screen and key it over a transparent background? The end user of the image wants it delivered with a transparent background. Anyone?
Posted: Thu, 1st Apr 2010, 9:59pm
Post 2 of 16
No problem. To export a picture with alpha channel (transparent pixels), simply leave the background empty and export your canvas. Make sure to use an image format that supports alpha channels, such as PNG.
Posted: Thu, 1st Apr 2010, 10:06pm
Post 3 of 16
Ok, I'm with you until you get to the format issue. Are you say that I need to use that format for my Foreground image, or do I need to export the finished prodect as a PNG (or whatever)?
Posted: Thu, 1st Apr 2010, 10:19pm
Post 4 of 16
Your foreground image can be any image supported by PhotoKey.
Your exported image, however, must support alpha channels. Otherwise, the exported image will have a solid white background instead of a transparent one. If you choose the PNG or TIFF export settings, you should get the results you are looking for.
Posted: Thu, 1st Apr 2010, 10:32pm
Post 5 of 16
Oustanding...can't thank you enough!!!
Posted: Thu, 1st Apr 2010, 10:41pm
Post 6 of 16
No problem, glad you're enjoying the product! If you have any additional questions, you know where to go
Posted: Fri, 2nd Apr 2010, 5:29pm
Post 7 of 16
Well, now that you mentioned it, I followed your instructions, and when I open the image in CS4 the background does not appear to be transparent. What should it look like? It looks to me like the BG is filled with distorted shades of browns & blacks behide the foreground image. I know that's a terible description, but that's what it looks like. I thought (and maybe I'm wrong)..that when I opened the image in CS4 I would only see the foreground image...maybe I'm wrong. Any thoughts?
Posted: Fri, 2nd Apr 2010, 5:50pm
Post 8 of 16
You exported to TIFF instead of PNG, right?
There is a weirdness with how Photoshop handles the transparency info in TIFF files that is being looked into. Open it in any other program and the transparency will work fine. In Photoshop, look in the channels palette, and you will see an alpha channel there containing all of the transparency info intact, but it doesn't get applied to the image for some reason.
If you export to TIFF, it will work as expected, otherwise you can use the alpha info in the TIFF document to create the necessary transparency in Photoshop.
Posted: Fri, 2nd Apr 2010, 6:14pm
Post 9 of 16
Yes I exported to TIFF, not sure I understand what you mean by:"otherwise you can use the alpha info in the TIFF document to create the necessary transparency in Photoshop".
Posted: Fri, 2nd Apr 2010, 7:08pm
Post 10 of 16
As I mentioned, its all recorded in the alpha channel of the TIFF file. Look in the channels palette and you'll see that its there. You just have to apply it to the image to make those bits actually transparent.
Posted: Fri, 2nd Apr 2010, 7:30pm
Post 11 of 16
OK, bare with me here...what do you mean "apply it to the image to make those bits transparet"? Apply what & how? Sorry!
Posted: Fri, 2nd Apr 2010, 8:27pm
Post 12 of 16
Sorry, I was assuming if you were a Photoshop user that you were familiar with alpha channels. The easiest way, if you aren't, is just to export from PhotoKey to a PNG instead of TIFF. Then you don't have to worry about it.
Alpha channels are channels that store transparency data for an image, just as the RGB channels contain color data for the Red, Green, and Blue channels. The TIFF file you exported from PhotoKey has an alpha channel containing all of the transparency data you set up in PhotoKey, it just isn't being applied to the image by default. So you need to tell Photoshop to use it as transparency data.
Firstly, the whole issue seems to stem from the fact that Photoshop turns the single layer in the TIFF file into a background layer, which doesn't allow it to contain transparency. So step one is to convert the background to an editable layer. Double-click the layer in the layers palette, then hit enter. Its name will change to layer 0, if I recall correctly, and that takes care of the that step.
Next, you need to apply the alpha channel to the layer. Make the alpha channel your selection by opening the Channels palette and command-clicking its thumbnail. If you are on Windows, I think you control-click, but I'm not certain of which modifier key to use. Once you have it selected, switch back to the layers palette, and create a layer mask using the selection you just created, by simply clicking the Layer Mask button at the bottom of the layers palette. That should do it.
I always use PNG so I've not actually run through this process in quite a while, but I think that coverts it. If it doesn't work for you, let me know and I'll open up Photoshop and figure it out for you.
Posted: Fri, 2nd Apr 2010, 11:25pm
Post 13 of 16
OK, I got it. It worked perfectly. CLEARLY I have a lot to learn. Thank you Axeman & Rogolo, I appreciate the time you took to help.
Posted: Sat, 3rd Apr 2010, 3:04am
Post 14 of 16
Awesome! Glad I remembered the process correctly.
I'm sure you'll get the hang of it soon. We are all still learning, don't forget.
Posted: Thu, 29th Apr 2010, 9:55pm
Post 15 of 16
For video output to retain the alpha channel, what QT codecs can be used? I just got CLP and have been playing with it, but would like to export some keyed greenscreen and use in FCP. Not sure which codec to use for rendering. I did see the option to keep the alpha, but I asume I also have to have the right codec as well.
Posted: Thu, 29th Apr 2010, 11:05pm
Post 16 of 16
You have posted this question in the entirely wrong forum. This forum is specifically for PhotoKey questions. There is a separate forum entirely for CompositeLab Support questions. Please try to keep your posts in the right area for the software you are working with. Thanks.
In the CompositeLab Support forum, there is a FAQ post at the top, which includes a link to an article in the knowledgebase dealing with how to render and retain alpha channels.
It should answer your question. If you need additional help, please let us know in the CompositeLab forum.