INF 385T Advanced Digital Imaging

Creating Sustainable Collections

April 7, 2008

Housekeeping and announcements

• Margie Compton is coming next week– Happy hour at Scholz after class

• Academy Film Archive is looking for interns for the summer!– Email resume, 3 references, and cover letter to

Kelly Chisholm: kchisholm@oscars.org

The Horse in Motion, by Eadweard Muybridge, as an animated sequenceMuybridge’s original still images were taken at the Palo Alto racetrack on June 19, 1878. Muybridge reportedly won a bet with a friend who held that at no point were all four of a running horse’s feet off the ground.

Film into video

• Film: A sequence of similar images that, when projected or viewed by means of an intermittent shutter mechanism, creates the illusion of realistic motion

• Video: Also a sequence of still images that create the illusion of motion when viewed in succession…but televisions and computer monitors don’t have a shutter!

Interlaced video

Alternating fields are combined (interlaced) to compose frames of video. NTSC standard is 29.97 progressive frames/second (30 interlaced frames). PAL/SECAM video runs 24.93 progressive/25 interlaced frames/second.

What issues does this create?

• Frame rate conversions (there is no one standard frame rate for film!)

• Visual differences when watching telecined footage on progressive (us. computer) vs. interlaced (us. television) monitor

• And then, of course, there’s high-def…

Moving right along to aspect ratios…

• Since 1917, there have been at least 6 frequently used aspect ratios (image proportions) for film– Not always easy to identify full-frame, unmasked films– Full silent aperture and Academy ratio very similar,

but not identical – an issue in projection/viewing• Widescreen and anamorphic standards pose the

biggest problems for film-to-video transfers and hi-def conversions (up or down)

• These are especially problematic when multiple formats are mixed in the same project (ex: documentaries w/archive footage)

Training your eyes to assess film and film transfers• Identifying film when it’s being projected– Look for grain quality in medium-value areas– Dirt, hair, flecks in light areas, esp. at head and tail of reels– Dark areas that are even or transition smoothly (saturated

exposures may have “pooled” darks or “blown out” highlights)

– Changeover cues (the “cigarette burn”) in the corner– Light beam from projector in booth will not be as steady as

during digital projection (may come from different window, depending on the booth); edges of projected image may show some motion too

– In bad cases, you may see obvious or midframe splices

• Identifying and evaluating digital projection– Rock-steady projected image– Absence of dirt or scratches– Texture of the image is different—grainless and

smooth– Color range may be somewhat different—whites

may be creamier or more opaque-looking, blacks flatter, less inky than in a film projection

• Assessing transferred film– Look for dirt, specks, or hairs (esp. in large, light

areas or around edges)• Keep your transfer equipment very clean!

– Watch large dark areas and, especially, backgrounds for digital artifacts: blocking, chunking, pixelation, and flattening

– Compare relatively still scenes with scenes that have a lot of action or motion in them, both small and large movements