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Old February 20th, 2003, 12:58 PM   #1
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Zooming still images jerk somewhat w/Premiere

I feel like I've tried everything to avoid minor jerky movement while zooming still images in Premiere. It looks like a field issue to me, but I've tried flicker removal, softening the image, etc., etc.

It is minor, but very anoying to me.

I would attribute it to the nature of video except it is entirely reasonable to expect a perfect zoom if I were shooting an 8x10 print with my camera and zooming, for example vs. having an electronic file and using the motion control in Premiere.

Am I missing something? The photos are scanned, saved to an appropriate size that corresponds to the percentage of zoom I'm using.

I'm positive it's not a playback issue...I can do lots of other much more complicated effects without a hitch.

Thanks.
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Old February 20th, 2003, 05:10 PM   #2
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If it is a still or scan I don't understand why you are looking at
interlacing: it is not interlaced. Make sure Premiere understands
that it is a progressive source.

What resolution is your picture, what file type?
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Old February 21st, 2003, 08:02 AM   #3
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I've tried a number of file types, but usually use .jpg's. For full frame, "non-zoomed" use, 720 x 540. If I know I'm going to do some sort of move, I increase the size in proportion to the percentage of enlargement I'll use.

Full frame still images look great. Moving smaller still images seem fine (but could be less noticeabe because they are smaller?)

I've tried the "flicker removal" only because the probem seems to have the same characteristics as "fine line" flicker as the image enlarges.
You lost me on the progressive source comment.

Thanks for your help.
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Old February 21st, 2003, 08:14 AM   #4
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What I've experienced isn't exactly jerkiness, it is a sort of artifacting due to jaggies in diagonal lines on moving stills. Looks somewhere between a minor jerkiness and a sort of shimmering.

I've had the same problem in Premiere and Vegas. I have just chalked it up to DV and 4:1:1 color space. The images may be higher resolution stills but at some point they have to be converted by the software to NTSC DV, with all the limitations that that implies.

I may be all wong here. (I often am.)
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Old February 21st, 2003, 08:26 AM   #5
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Rick, I think we're on the same page. What doesn't make sense to me is that I can do a perfect slow zoom using the camera and an 8x10 or larger print, but it looks imperfect when doing it as a digital "effect".

Watching "Biography", they often use slow zooms and pans on still images and it's flawless. Judging by the complexity of the moves, I'm sure it's done digitally, unless they have a motorized camera stand and compound (ie. Forox, Oxberry).
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Old February 21st, 2003, 08:34 AM   #6
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Perhaps Premiere is not doing such a good job? Maybe try out
a demo of another NLE to see what kind of results they get?
(the best one to try is probably Vegas 4.0.
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Old February 21st, 2003, 08:35 AM   #7
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I used to have this problem with Premiere, until I found a way around it. This is what I do to get smooth zooms and pans on stills in Premiere.

First, I don't use Motion, but instead the Image Pan transform. Motion loses resolution on zooms, Image Pan does not.

Next, using Photoshop or another paint program, I resize (sometimes called resample) the still to the maximum size Premiere will accept, i.e. a square image would be 4,000 x 4,000 pixels, a rectangular image would have its longest dimension set to 4,000 pixels.

Finally, I save the image as an uncompressed TIFF file, never as JPG or BMP. (In addition to providing a high-quality image without compression artifacts, the TIFF format can maintain an alpha channel, which I tend to use a lot for titling sequences and major transitions).

Using this technique, I can zoom in on a still image by 400-500% without blockiness or motion artifacts (obviously, though, resizing won't add detail that wasn't there to begin with -- I try to scan images to the appropriate size whenever possible).

My zooms and pans are liquid smooth and artifact free. The only downside, it takes Premiere quite some time to handle images this large -- display of the timeline can slow down and, of course, if rendering is necessary, it takes much longer to process these large images than it would if they were 720 x 480.
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Old February 21st, 2003, 08:42 AM   #8
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Thanks, Paul. I'm going to try it right now.
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Old February 21st, 2003, 10:13 AM   #9
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Paul, you are the man!

I tried resaving an existing fairly large .jpg to a .tif and using Image Pan...it was much better but still a little ragged at the first part of the clip, then smoothed out considerably.

Then, I rescanned the image at 4000 pixels wide and saved it as a .tif with no compression. Outstanding results!

It takes 5 times longer to render vs. using "Motion", but the result is 500 times better...very flluid. Plus as you mentioned, there is no loss of picture resolution.

What resolution do you use in Photoshop? I kept my test at 300 pixels/inch . Would reducing it to say 100 be counter productive? Just trying to make it process a little faster. I'm using grayscale images...color ones would slow up the works even more.

My thanks to you and this forum.
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Old February 21st, 2003, 10:31 AM   #10
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Quote:
What resolution do you use in Photoshop? I kept my test at 300 pixels/inch . Would reducing it to say 100 be counter productive?
I don't bother with the resolution setting unless I'm going to print the image as a hard copy still. Premiere doesn't care about resolution or size, only total number of pixels. If I'm printing hard copies I set it to the resolution of my printer. Otherwise, I just leave it at whatever it was set to the last time I used the software.
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Old February 21st, 2003, 11:14 AM   #11
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Paul,

Thanks. I may try reducing the resolution while keeping the pixel size as you suggested simply to reduce the file size. Not sure if it would effect the rendering time or refresh rate on the time line or not.

Once again, thanks for the great info. I thought I'd sampled every video effect Premiere had, but I missed this one.
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Old February 21st, 2003, 05:07 PM   #12
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I may try reducing the resolution while keeping the pixel size as you suggested simply to reduce the file size. Not sure if it would effect the rendering time or refresh rate on the time line or not.
I don't think changing the resolution would have any effect on the size of the file. Resolution tells the output device how big to display the picture, e.g. an 8 x 10 photograph, scanned at 100 dpi, results in a picture 800 x 1000 pixels, and a file size slight larger than 800k A 4 x 5 photograph, scanned at 200 dpi, results in a picture containing the same number of pixels and the same file size, i.e. 800 x 1000 pixels, resulting in a file slightly larger than 800k (it's slightly larger because different storage formats append headers which contain a variety of information, including the resolution and/or size of the image).

If you're resizing (or scanning) everything to a maximum 4,000 pixel resolution, the file size won't be effected, since each picture will have the same number of pixels, i.e. 4,000 x 4,000 or 16M, regardless of resolution.
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Old February 21st, 2003, 05:53 PM   #13
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I played around with this a little today. Using uncompressed images helps a lot. Seems obvious now. JPG is a compressed medium, as is DV. No need to combine the two. Thanks for the tip, Paul.

The other thing that I found that worked well was deinterlacing the final file. I tried with both Canopus "old movie filter" using the "blend" option and Vegas, also using the "blend" option.

I used a photo that was handy and it turned out to be a tough one. The photo was my son on a skiing trip. In the background are trees covered with snow, resulting in a complex pattern of light and dark. The foreground looked fine. The background however had a pronounced shimmering effect as I zoomed in or out. This was worst witha jpg file. It improved but did not go away with a targa file. Once I deinterlaced, it was a reasonably smooth zoom. Of the two deinterlacing methods, the Canopus was slightly better than the Vegas.

For what it is worth.
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