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I need help with a math problem, essentially: How much can I scale my layers or comps (expressed in percentage) in After Effects before I've passed the threshold where pixel interpolation will occur? Here's the details:
I capture all my still images from my DSLR at the size of 2256 x 1504. This size is larger resolution than my largest final destination goal of 1080p, which is 1920 x 1080. So I have some wiggle room to scale up a scene if I need to in post-production.
If you're familiar with After effects transforms, The layers start at 100% scale, and you can make them bigger by raising this percentage up. But how can I figure out how much is too much? At a certain point, After Effects will begin interpolating pixels, sacrificing image quality.
At the end of the day, it will probably look fine even if I pass this threshold, but it would just be nice to know when I pass it.
I hope this makes sense, I can't think of how to get this percentage.
I think the percentage that you would be looking for is 117,5%
What you can actually do is the reverse though.
Make a composition that is 1920x1080 and import your shot. After effects will not automatically fit it to that composition but just put it in at 100% scale of the original footage (in your case 2256x1504) Then it is automatically at your max. You can scale it down from there. Does that make sense?
If I don't want to zoom in or pan around the frame, I just import the full size image (into TV Paint in my case) and scale it down to 1920 pixels wide. No percentages, just set the dimensions. Don't know if AE can work that way. Then I crop top and bottom to make it 1080 high. I like to do any fixups like keying or wire removal at full size before scaling down.
If I do want to crop in I load up the full size image and make a rectangle at 1920 x 1080 that I can move around the frame to work out where I want to crop it to. (Or just use the Crop tool if it works like that, with a rectangle showing the selection the you can position where you like.) If I actually want to move around during the shot, either a zoom in or pan around, I usually load the full image into Lightwave 3d and map it onto a 2 x 3 ratio rectangle object (probably not the usual method, but it works for me with what I have). Then I can move the virtual camera around. Before i do that, though, I look at what a 1920x1080 crop would look like in Photoshop, after Effects, or TV Paint, so I know not to go any closer than that. You can get away with enlarging the image a little bit if you have to, like if something on the side of frame went wrong and had to be cropped out, but you wouldn't plan on it.
Generally I shoot at Large size, or at least bigger than you do, to give me more room to move. My Canon's Medium would be bigger. Are you shooting Small size? My oldest DSLR camera was a 6 megapixel Nikon D40, and it shot 3004 x 2000 at Large setting and I think Medium was similar to what you are shooting.
Jasper is partially right. Create your AE comp at 1920 X 1080, then when you drop your footage into the comp it will go in at 100% scale, which means it spills over the edges. There's a little box at the bottom left of the viewing panel that gives the scale of the comp image. If you put this to 25% or less, you should see a white border around the edge of where the footage extends to, so you can move it around or scale it down, holding down the shift key to keep proportions.
But if you scale the layer above 100%, you will surely lose resolution. If you want to zoom in , then you need to capture much bigger, even all the way up to the max in your DSLR, which is about 5k and allows you to zoom in to about a quarter of the frame before dropping below 100%. In that case you would import the footage at 100% and set the max zoom in by sliding it around in the composition, then scale it down to give the zoom out point.
Thanks for taking the time to post some of these ideas, and I think I've got it figured out. I'll explain my workflow a bit to clarify.:
Since my DSLR captures are 2256 x 1504, which Canon calls 'Small Superfine', I don't think it's good to place my large images into an AE comp at 1920 x 1080 and scale down. I created my own custom comp size for Small Superfine and use that so everything is at 100% scale.
When I know ahead of time I'll want to do a scaling dolly in/out, I up the resolution to Medium, to get the extra resolution. (But those frame disk sizes in MB, YIKES! )
For final output, I render 100% uncompressed AVI's and use Adobe Media Encoder to encode and sample down to any format I need.
So here's what I think my scaling threshold is: ~15%. That's how much bigger my frames are from 1080p. I know this because it's ~85% scale that puts my frames into a 1080p composition.
Let me know if this stands to reason.