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strip image from moving film

Sep 20, 2012 10:23 AM

Tags: #after #effects #photography

How can I take a single pixel wide vertical strip from the same position on each frame of a film and line them up inorder side by side to create an image?

 
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  • Currently Being Moderated
    Sep 20, 2012 10:45 AM   in reply to nicolaharkness

    You would probably have to rig something with expressions - a linear wipe, that "crops" only 1 pixel plus some code on the position that offsets each layer by that 1 pixel column and even more expressions for time-remaopping so that each frame is correctly represented in its pixel column. That would be based on the layer index as the multiplier and as you duplicate the layer, it would offset automatically. It may just not be particulalrly practical to have 1920 layers to fill a HD comp or even more. And the expressions will make things slow to begin with. Other than that feel free to experiment with Time Displacment as already mentioned here: http://forums.adobe.com/thread/1068924?tstart=0

     

    Mylenium

     
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    Sep 20, 2012 11:56 AM   in reply to nicolaharkness

    You could also import the footage into Photoshop as files and do it manually.  Actions might help speed up the process, but it might take a while to figure out how to get it to work the way you want it. Also, try asking on the After Effects expressions forum and see if anyone has an idea about how to set up an expression that corresponds to Myleniums suggestion. 

     

    http://forums.adobe.com/community/aftereffects_general_discussion/afte reffects_expressions

     
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    Sep 20, 2012 12:05 PM   in reply to nicolaharkness

    I'm not aware of any software that specifically does this, but as Ben suggested, there may be a way with Photoshop actions as well. If you're not in a rush, I may give this a try tomorrow and come up with something in AE. It's too late in the evening now here and my brain is munched...

     

    Mylenium

     
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    Sep 20, 2012 2:38 PM   in reply to nicolaharkness

    I'm not exactly sure what you're trying to accomplish here. Could you describe the shot or process a little better.

     

    What I think you want to do is to take a single pixel vertical strip from frame 1 at column 1, then take another column of pixels from column 2 and frame 2 then do it again for column 3 frame 3, column 4, frame 4 and so on until you have one column sampled for each frame for the entire composition.

     

    I think that you then want to stack up these columns of pixels to create a single frame with each column being a different slice of time.

     

    You can do that with a gradient and Time Displacement. Just select a black to white gradient with black on the left and white on the right. Pre-compose that layer. Then take your footage and apply Time Displacement. Set the CTI indicator to the frame that is half the width of your composition. IOW, if the comp is 1920 X 1080, set the CTO to frame 960.

     

    Now adjust the time resolution to your frame rate and set the offset to the position of the CTI (960) by the frame rate (30) and you've got it.

     

    Frame 960 will have a column of pixels from each of the 1920 frames in your movie.

     

    Here's a screenshot of a single pixel line moving from the top of the frame to the bottom of the frame with time displacement applied. The comp settings are 872 X 486 @ 30 FPS.

     

    Screen Shot 2012-09-20 at 2.33.47 PM.png

     

    The gradient in the background is a pre-comp that is driving the Time Displacement.

     
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    Sep 20, 2012 5:21 PM   in reply to Rick Gerard

    That certainly seems like a much better way of automating that process than doing it manually in Photoshop.

     
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    Sep 21, 2012 12:14 AM   in reply to nicolaharkness

    Did you take a look at the Time Displacement solution. It's every bit as accurate as duplicating a layer 1920 times (for an HD comp) and fussing with the time and the slice with expressions.

     

    I still am not exactly sure what you are trying to do other than create a single frame with a bunch of time slices.

     

    The Time Displacement solution that I offered would also create a movie with this multi time slice image moving at the same rate as the movie that generated it.

     
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    Sep 21, 2012 9:01 AM   in reply to Rick Gerard

    I have to agree with Rick:  what visual look are you trying to accomplish?  It would take A LOT of frames to create a single frame.

     

    In my mind's eye, your process as described would yield a bizarre-looking, non-sensical single frame.  The ultimate look would depend on the motion in the original footage, of course.

     

    Or is this more of a, "Can AE do this?" sort of question?  If so, you have a few techniques offered.

     
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    Sep 21, 2012 1:05 PM   in reply to nicolaharkness

    I don't think you'll get the kind of image you want by taking 1 pixel wide slices of time. You'll end up with a time smear.

     

    Take a look at this short video of someone walking using the time slice method you're describing.

     

    Screen Shot 2012-09-21 at 1.02.00 PM.png

    http://www.youtube.com/watch?v=01JzIIJGaSg

     

    If you have a sample of what you want it might help us to point you in a more efficient direction.

     
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  • Currently Being Moderated
    Sep 21, 2012 1:49 PM   in reply to nicolaharkness

    ...and again, I'm in agreement with Rick: I don't think you'll get what you're after.

     

    You say you're shooting video, and you say the subjects move at about 60 mph.

    At what frame rate do you intend to shoot?  The fastest frame rate on typical video cameras is 59.94 frames/ sec.

     

    Let's say you shot a still at 1/60 sec.

    If you hold the camera still, the subject in the shot will have motion blur.

    If you pan the camera to follow the subject, the background will have motion blur.

    Does this constitute what you are calling a realistic image?

     

    I'm still having trouble understanding how the technique you propose will yield anything useful.  It certainly won't look realistic.

     
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    Sep 22, 2012 7:26 AM   in reply to nicolaharkness

    You are misinterpreting the technique that is used here. The photographer is using a slit scan panoramic camera but is panning at the same speed that the people in the shot are walking.

     

    These cameras have been around as long as there has been photography. The film back is curved and the lens and a slit at the focal plane move by a gear mechanism moving the slit over the film. We have a photograph of my great grandfather in Park City, Utah in the 1880's shot with one of these cameras. It's a group shot of all the miners working at the mine but great grandpa is on the left side of the group and also on the right. He just ran behind the group after the lens passed him and got to the other side before the lens did. They used something like this:

     

    http://upload.wikimedia.org/wikipedia/commons/6/69/Al-vista_camera.png

    Here's one from the 40's

     

    http://collectiblend.com/Cameras/images/Meopta-Pankopta-Panorama.jpg

     

    Normally, the camera is stationary and the lens and slit moves. In the case of your example, the camera is panned in the opposite direction the lens is moving so that the moving subject, the people, stay centered in the frame, and the background is blurred. This also isn't a new technique. There's a very famous photograph of the 1948 olympics that was shot like this.

     

    You can achieve this effect easily with a standard video camera and Time Warp by simply panning with the subject. It's dark outside now, but in an hour or so I'll shoot something with my iPhone and post an example. With a little clever pre-comping I can even simulate the panorama. You may even be able to do this with the new panoramic shot feature with the iPhone iOS6. I'll even give that a shot. You'll never get this effect with a high shutter speed, a stationary camera and thousands of frames.

     

    In 1974 I did a story on a Seattle firefighter that built his own camera that used 10" wide roles of aerial photography film to shoot amazing panoramas of Seattle.

     

    Here's a panoramic camera you can buy today for $275 that will do what you want to do.

     

    Here's one for under a hundred.

     
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  • Currently Being Moderated
    Sep 22, 2012 10:01 AM   in reply to Rick Gerard

    Well, all that theoretical stuff aside, here's what I've cobbled together:

     

    http://www.mylenium.de/stufffiles/look_color_strip.zip (CS4 and above)

     

    Maybe it's of some use, after all. Though, as Rick and Dave said, if you really want to produce a slitscan effect, you'll have to do a lot more than just slice up a sequence of film frames.

     

    Mylenium

     
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    Sep 22, 2012 11:37 AM   in reply to Rick Gerard

    I had a thought this morning about achieving the effect with a video camera doing a pan. In that case the frame rate is the problem. No matter what you do you're only going to have as many time slices available that the camera can produce. If you wanted a 1920 slices of time over a 3º pan then you would need to shoot a 1920 frames or about one minute and 4 seconds at standard video frame rates. If your camera was positioned so that you would see 50' of the finish line and your subject was traveling 60mph (88 feet per second) it would only take about .56 seconds to cover the field of view you are interested. That means 1920/.56 or about 3300 frames per second. At that frame rate you wouldn't get the nice blurred background, but you could get the same distortion you'd get with a slit scan panoramic camera panning to follow the action.

     

    I did check out the iPhone slitScan camera option but it only samples about every 1/10 of a second so that doesn't work either.

     

    Mylenium.. I checked out your project file. I think it's broken. The Color strip footage never moves into the frame and isn't offset as layers are duplicated.

     
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    Sep 22, 2012 11:04 PM   in reply to Rick Gerard

    Mylenium.. I checked out your project file. I think it's broken. The Color strip footage never moves into the frame and isn't offset as layers are duplicated.

     

    Works fine for me - getting nice temporally offset strips from the colored balls and all sorts of funky patterns and loading in some footage in the source comp also makes it beautifully striped....

     

    Mylenium

     
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    Sep 22, 2012 11:11 PM   in reply to Mylenium

    Here's a screenshot of the project including settings used:

     

    23-09-2012 08-09-59.jpg

     

    Again, works perfectly on my end...

     

    Mylenium

     
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  • Currently Being Moderated
    Sep 23, 2012 7:05 AM   in reply to Mylenium

    Think I may have found the problem. Your example file opens like this:

    Screen Shot 2012-09-23 at 6.56.13 AM.png

    Seems to be missing the Strip Sample Increment? check box. Must have zipped up a previous version. There are no missing or broken expressions in the sample comps.

     
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  • Currently Being Moderated
    Sep 23, 2012 7:26 AM   in reply to Rick Gerard

    Ah, my bad. Zipped up a prototype version with a variable angle control that I didn't finish. Correct version now in place. Please download again. Sorry for the confusion.

     

    Mylenium

     
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  • Currently Being Moderated
    Sep 23, 2012 8:49 AM   in reply to Mylenium

    Thanks for this sample. That's very clean work. Render times, as expected, are fairly imposing.

     

    There are some really good ideas in your expressions.

     
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    Sep 24, 2012 11:24 AM   in reply to Rick Gerard

    I also just wanted to add my favorite panoramic camera, the Soviet Horizont.  Here's a really good condition one on ebay at Buy it Now for $300.

     

    http://www.ebay.com/itm/HORIZONT-Horizon-Russian-35mm-Panoramc-Camera- /330762022900?pt=Film_Cameras&hash=item4d02f3eff4

     

    A bit more info about the camera:

     

    http://www.sovietcams.com/index.php?686983092

     
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  • Currently Being Moderated
    Sep 24, 2012 4:49 PM   in reply to nicolaharkness

    Mylenium's solution is very clever but it's not going to give you any different effect than Time Displacement and a gradient.

     

    If the bike is moving and the camera is still then the time slices will slice up the bike into strips and keep the background the same. To make a complete bike you need to be panning with the bike. When I get a moment I'll post a shot that shows what I mean. There's no way to hold the camera still, have the bike move and then slice up time and get a complete bike. Each time slice will only contain a small slice of the bike.

     

    There are digital slit scan solutions out there. They work exactly the same way a slit scan film camera does. You just can't do this with technique with a standard full frame camera.

     

    Here's the shot with horizontal time slices (because the cars are moving toward and down in the frame.

     

    Screen Shot 2012-09-24 at 4.44.01 PM.png

    Notice how the car in the middle lane on the left is chopped into a bunch of frames but the cars in the right lane moving away are shortened way up.

     

    If I get a chance later tonight I'll slice up a shot where the camera is moving. The subject will be relatively undistorted but the background will be cut up into slices. If you look closely at the image above you can see he time slices in the center barrier and the lane markings caused by camera movement.

     
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  • Currently Being Moderated
    Sep 25, 2012 1:53 PM   in reply to nicolaharkness

    With a 1 pixel strip you would still see 30 pixel tall slices because the video was 30fps. It would be meaningless to slice any smaller.

     

    In regards to your wanting to get a sharp image of the bike I think you still are missing something. If the camera is not panning or moving with the bike at approximately the same speed then you're going to get slices of one part of the bike only.

     

    For example, if the camera is still and it moves from left to right and it takes 1 second to cross the frame. Let's say your time slices see a strip of the bike that's 1 inch wide. The resulting image would be that one inch of the bike repeated all the way across the frame. It would be just like the image of the car above that's not really a car, but just a portion of the car repeated many times.

     

    This would be nothing like the image you showed us as an example. There's no way of generating that kind of image without approximately matching the speed of your subject.

     

    Shooting at a high frame rate without panning would only give you smaller strips so the portion of the bike in the strip would be narrower.

     

    You'll end up with something like this:

     

    Screen Shot 2012-09-25 at 1.45.39 PM.png

     

    The single column of pixels just right of my daughters nose is repeated across the frame. That's about what you'd get with a stationary camera.

     
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  • Currently Being Moderated
    Sep 25, 2012 3:28 PM   in reply to nicolaharkness

    This is a very weird hybrid manual/digital technque I was playing with a lot last year to make aniamtions:  Try taking a sharp image of someone riding the bike with a very fast shutter.  Then move it across the bed of a scanner While it's scanning so that the scanner captures and distorts slices of the image as it moves.  Depending on how fast and when you move the image with the scanner you could potentially control how distorted the background is in relation to the subject.  I know this is a totally different technique than what you were originally after, and it will no doubt render different results, but I feel like it might get you in the ballpark of what you want.  Also, one thing I realized when doing this is the higher you set the dpi on the scanner, the slower it will scan.  You could also shoot multiple pictures to create a panorama the size of Adam Magyar's work with a normal DSLR camera on a panning tripod head.  Then assemble those images in Photoshop with Photomerge, print out your panorama and drag it across the scanner to distort it.  Here's an image I made last year by just moving my face across the scanner bed :-) 

     

    Face_Forum.png

     

    The scanner only focuses on what's directly touching the bed, but if you had a photo you could hold it down is you move it so it would be sharper.  As I said it's a totally different technique, but it's fun and might give you more control.

     
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  • Currently Being Moderated
    Sep 27, 2012 8:26 PM   in reply to BenMarkus

    Not to beat a dead horse but this is what I got when I shot a short video of my daughter riding beside me. Sliced it up into a bunch of vertical slices in time. You can see the wave created by her knee, and the extended arm because we were not perfectly synced for the 6 seconds of this shot:

     

    Screen Shot 2012-09-27 at 8.17.16 PM.png

     

    For even more fun take a peek at this video. You can see the slices develop over time. If I was perfectly tracking her head for example, it would be relatively distortion free throughout the video but the wavy image of her knee would remain.

     

     
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