How exactly do you capture the difference between different media? When we first started thinking about showing the difference between film and digital video disks we assumed that the image on a 35mm film print would be far superior to that on a DVD. But we were wrong–the DVD frames were crisper, showed a wider color space and range than the film.
For lossless_1 we scanned the 48 frames sequence of Dorothy clicking her heels together from a 35mm print at 2k resolution (2048×1536 pixels). We then extracted the same frames from the newest PAL digital video disk. We then calculated a new sequence of frames from the difference between the scanned print and extracted DVD frames.
Here is a diagram illustrating how the overlap of two media might be expressed.
Both media contain artifacts. Film prints take on artifacts (scratches, etc,) every time they are played. DVDs aren’t changed by performance, though the procedure of reduction and backfilling of image data provides its own world of artifacts.
Interested in difference operations? Here is a gallery showing the most common composite operators.
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