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  1. Member
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    Gents:

    Please help me minimalize the damage!

    My wife helps me film over the weekend, however she did nothave much success keeping the tripod straight and level which I only discoveredafter we were finished recording. We shoot a fair distance away from the stageso any deviation greater than 1 degree from being perfectly level - horizontal is verynoticeable when fixed in post.

    My goal is to not to sacrifice resolution, sharpness orpixel density in the process of attempting to correct the affected clipsorientation, retain its' 16:9 ratio & continue to fill the frame with theoriginal image.

    Rotation generally requires scaling/stretching/reducing the image tofill-in the black space/triangles that result which impacts visual quality atleast to my eye.

    Instead, I'd rather have a small black border around the entire framethen lose yet more detail.

    Apparently cropping doesn't work as needed with rotation.The triangles/black space/gaps created by rotating the video still remain afterthe crop.

    What can be done to create a black border as stated abovewithout having to zoom in on the footage?

    Are there any options?

    I'd welcome a solution!

    Thanks in advance.
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  2. Rotate, and overlay a black border to cover up the edges

    e.g make a black border in photoshop or image editor (alpha channel or "transparent" in the middle), put it on the top track above your video

    Depending on the shot composition, there are other techniques used to fill in the gaps, such as inpainting, photoshop manipulation. For example, if the black edges after rotation occur only on static background elements, and the tripod is locked off, no movement at all - it shouldn't be too much work
    Last edited by poisondeathray; 1st Apr 2013 at 14:25.
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  3. Member Cornucopia's Avatar
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    BTW, for best rotation interpolation quality, I'd use an AVISynth script (or AfterEffects), not the rotation feature of your standard editor (though you probably would need to know the exact angle graphically first).

    Scott
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  4. Apply a 4 point garbage matte effect to your clip. By carefully locating your corner points you can "counteract" the rotation.
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  5. Member
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    Great tips given to a person who doesn't know or own Photoshop or After Effects. Never used a garbage matte either.

    Scott, do you know of or have an Aviscript where I could just input the angle?

    Poison Death ray ( wish I knew your real name),

    I like your suggestion also. Would you please point me out to any online tutorials that may get me jumpstarted?

    The best image editor I have knowledge of is Lightroom which is geared towards photography correction & enhancement.
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  6. Member budwzr's Avatar
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    Originally Posted by smrpix View Post
    Apply a 4 point garbage matte effect to your clip. By carefully locating your corner points you can "counteract" the rotation.
    Oops, my mistake.

    ==============================
    Hey, there's a doodle pad down here!
    Last edited by budwzr; 1st Apr 2013 at 21:23.
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  7. good idea smrpix

    canon gl2 guy - the garbage matte is an effect in PP . IN the effects search type in "garbage matte", and apply to your footage . You just adjust the parameters , top left, top right etc... It's very easy to use
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  8. Originally Posted by Canon GL-2 Guy View Post
    do you know of or have an Aviscript where I could just input the angle?
    http://avisynth.org.ru/rotate/rotate.html

    Code:
    WhateverSource()
    Rotate(angle)
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    If the rotation is not drastic you could try a perspective correction effect. Move the corners until the stage is "level".
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  10. Here, quick guide.

    1) In the effects controls rotate your shot to straighten
    2) Locate the garbage matte effect and drop it on your clip
    3) Adjust the corners of the garbage matte to hide the triangles and create a black border

    The effect can be saved as a favorite for reuse. No resizing, no intermediate render.

    Click image for larger version

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  11. Member budwzr's Avatar
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    I thought you people meant using "corner pinning" in a 3D space, and warping, but actually you're just cropping using a fancier tool, right?

    So the terms "Counteract Rotation" and "Perspective Correction Effect", used above, are "sizzle"?
    Last edited by budwzr; 2nd Apr 2013 at 09:45.
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  12. Member
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    Originally Posted by budwzr View Post
    I thought you people meant using "corner pinning" in a 3D space, and warping
    Yes, this is what I meant by a perspective effect. If the camera tilt is not too drastic, just pull down the corner of the frame where the stage line is highest to level it out. If you're working with HD video, the slight stretching shouldn't cause very much resolution loss, and it would only be at that one corner. If you have to warp the video too much to level the stage it will probably become too noticeable and you will need to resort to rotation and cropping as others have noted.
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  13. Originally Posted by Khaver View Post
    Yes, this is what I meant by a perspective effect.
    No, this is simply cropping away the triangles and leaving a border. Perspective in the case of a linear rotation would end up being the same as a zoom which OP is trying to avoid.


    Originally Posted by Khaver View Post
    If the camera tilt is not too drastic, just pull down the corner of the frame where the stage line is highest to level it out.
    That's interesting though. More of a warp.
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  14. Member
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    A quick update:

    Thanks for all of your suggestions.

    Please allow me some time to absorb, experiment and to go through the options.
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  15. Yes, parallelogram (and other simple) distortions can be used to approximate small rotation angles. The technique was sometimes used in early video games because it's computationally inexpensive compared to a rotation.
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