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JPG’s flicker
I have had some complaints of people who view my DVD’s (made with Architect)that when viewed on their computers the still images flicker slightly.
Is there a certain size, resolution, DPI and so on that I should use to avoid this?
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6 Replies
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Are these images that you’ve scanned in or do they come from a digital camera?
My usual rule of thumb is, unless you’re doing extensive zooming in on the image, that the pixel size (ignore DPI as it has no relation to anything in video) should be no larger than twice your project size.
For standard definition video, that would be 1440 x 960 pixels.
If you have images from a digial camera, they’re quite often 3,000 x 2,000 pixels (sometimes larger).
use an app like IrfanView to do a batch size conversion to shrink them down.
If you’re scanning images, I’ve found that 1″ of image = 100 pixels at a scanning resolution of 100 DPI.
This is too small for a standard 6″ x 4″ (W x H) image so, unless I need to zoom a lot, I scan at 150 DPI.
With a 6″ x 4″ picture, this gives an image that’s 900 pixels x 600 pixels which is slightly over the 720 x 480 needed.
This gives you a decent sized image that be zoomed in on a bit without degradation.Keeping the image size down is the best cure for reducing flicker.
You can also use the “Reduce Interlace Flicker” option in Vegas to reduce the shimmer.
Another tip is make sure the images fall in the DV colour range of 16-235. Most (if not all) images take the full 0-255 range. Here’s the fix to change this. Click the FX icon and select “Color Corrector (Secondary)”. In the Preset window, select “Studio RGB to Computer RGB”. Your images are now in the DV colour range so that extreme whites or blacks are no longer an isssue.
If it’s still objectionable, apply a very slight Gaussian blur (vertical only – set to 0.001) to the image. -
Muke,
Shouldn’t it be “computer RGB to Studio RGB” to limit to 16-235? -
D’oh!!!
You’re right Terry.
Thanks for catching that. -
Thanks so very much for the tips. I think it’s just what I needed. I very much appreciate the help.
Roger -
This is my fault in not mentioning this but I’m working with M2t files in HD. I’m thinking now that your formula for resizing will have to be adjusted… but to what?
And yes, I’m using digital photos rather than scanning. -
Roger, as I said earlier, make your images twice your project size. For HD, that would be 2880 x 2160.
If there’s no need for zooming, leave them at project size.Another hint is to save them in PNG format after the conversion.
This is the preferred format for Vegas and you’ll find that a timeline of large PNGs is easier on your computer than the same timeline full of JPEGs.
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