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View Full Version : shooting miniature stop motion for green screen: RAW or jpeg???



Nicholas Natteau
09-15-2012, 03:53 PM
I'm about to start shooting my first stop motion short film using green screen for a background.

I plan to bring my stills into Photoshop CS6 and/or After Effects CS6

Assuming the scene is properly lit for green screen, can I get a decent chromakey if I shoot jpeg or would I get much better results shooting RAW???

Amr Rahmy
09-15-2012, 04:52 PM
jpeg will introduce jpeg compression artifact, is there a reason your considering jpeg? it's a short film, it can't be file size or the program used.

Nicholas Natteau
09-15-2012, 05:32 PM
Correct Amr. I'm thinking the film will be no more than 2 minutes max. So are you saying that RAW is the way to go if you plan to chromakey the subject away from the background?

Amr Rahmy
09-16-2012, 06:17 AM
it will just introduce minor jpeg artifacts all over the image and compress to 8bit file. if there is no compelling reason for you not to choose raw, then why ask?

Nicholas Natteau
09-16-2012, 09:02 AM
But does the jpeg format make it more difficult to pull a chromakey? If so, then I would shoot raw. The reason I asked was because I know that RAW files are much larger and take more time to process, and my 2 minute shoot would involve 2,880 frames (2min@24fps).

Michael Carter
09-16-2012, 01:30 PM
Does anyone replying have any real-world experience with this scenario?

I do - using DSLR stills for green screen (in my case timelapse and some artsy shots).

JPEG is fine - a medium sized JPEG shot on the "fine" setting (Nikon nomenclature) is a nicer frame then you will get from ANY non-spielberg level video camera, as far as compression quality and frame size goes. At the highest JPEG setting "artifacts" just aren't there for these purposes. If you want total overkill use the largest image setting - but in my case "Medium" size is much larger than a 1080 frame.

I've keyed footage from many models of digital video cameras and made very nice final shots with varying amounts of work. All other factors being the same (screen and foreground lighting, proper exposure, etc) JPEGs just take all the work from keying. Work on image sequences at the full size of the JPEG and crop/output them to 1080 or 720. I wish AVCHD was half as clean as JPEG.

I don't know what the naysayers have been working with for this use - images from web sites? What was the situation where JPEG artifacts are worse than DSLR, AVCHD, or other motion compression schemes?

Sure, RAW will give you a stellar image, but the idea of converting that many raw files to add very little to the final product just seemed like a huge waste of time to me. Import a nice JPEG sequence into AE at full image size, convert the project to a higher bit depth if you need to grade it like crazy, pull your key and output.

Starting with 16-bit images sounds awesome, but your image is still one set of colors - the green of your green screen is basically the same color regardless of bit depth when talking stills - you don't have any of the issues of video compression. If you need to push it in grading, sure, up the depth in your project, not your camera. JPEG at high quality settings gives you an image that blows away any footage most of us have ever worked with.

All that said, these kind of forum questions can be informative (when answered by people who have actually worked with the subject in question), but not nearly as informative as testing for yourself. You should be able to have your answer in a matter of minutes after making a test set - good luck.

Nicholas Natteau
09-16-2012, 03:21 PM
Thank you very much Michael for taking the time to explain this. Will go ahead and test this coming week. Thanks again.