how many ways can you count your ks?
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November 14, 2006 SMPTE Meeting, Hollywood Section 1
How Many Ways Can You Count Your Ks?
Siegfried Heep
Modern VideoFilm
ASC / SMPTE Meeting, November 14, 2006
November 14, 2006 SMPTE Meeting, Hollywood Section 2
Topics to be Covered
• What is a Pixel?
• What is a K?
• DPX File Format
• Film Camera Apertures
• Projectable Image Area
• SDI - Serial Digital Interface
• Motion Picture Camera Imaging Sensors
November 14, 2006 SMPTE Meeting, Hollywood Section 3
What is a Pixel?
Picture Element
• Pixel Counts• Pixel Properties
November 14, 2006 SMPTE Meeting, Hollywood Section 4
Pixel Count, What is a K?
Kilo - metric modifier, one thousand units -
kilogram, kilometer, kilobyte, K (pixels)
Like kilobytes, pixels are binary addressed,
usually, one K = 1024 instead of 1000
2048 = 2K 4096 = 4K 8192 = 8K
1920 = 1.9K 7680 = ?
November 14, 2006 SMPTE Meeting, Hollywood Section 5
2K or 4KPixel Counts
2048 pixels wide
4096 pixels wide
3 vs. 12 Mega pixels
(quadruple the amount)
With square pixels, the width by the height is the Aspect ratio.
2048 by 1556 = 1.32 to 1
1920 by 1080 = 1.78 to 1
November 14, 2006 SMPTE Meeting, Hollywood Section 6
Pixel Properties• Components of color
– RGB, or YCrCb
• Bit depth per component– 8 bit, 10 bit, 12 bit, 16 bit
• Color Primaries and White Point• Level Scaling (data range)
– Video Level Scaling (with data Headroom) at 64-940 or Full Range (computer Graphics levels)
• Tonal curve (gamma)– gamma, linear, “log”, printing density
November 14, 2006 SMPTE Meeting, Hollywood Section 7
low high clipped applied twice
Picture is derived from NIST test frame
VIDEO LEVEL SCALINGGAMMA CURVE
Examples of changing settings
November 14, 2006 SMPTE Meeting, Hollywood Section 8
Typical Pixel Properties
HD
D-Cinema
November 14, 2006 SMPTE Meeting, Hollywood Section 9
Clear the palate with some nice fresh sorbet.
November 14, 2006 SMPTE Meeting, Hollywood Section 10
DPX File Format, Digital FrameSMPTE Standard 268
for storing digital images
widely used for Digital Intermediate and Visual FX
• “log” - actually printing density, like Cineon
• “lin” - actually a gamma setting
A bunch of pixels
10 bit Integer numbers (Code Values 0 - 1023)
November 14, 2006 SMPTE Meeting, Hollywood Section 11
Film Camera AperturesSMPTE Standard 59
physical dimensions on film
width A = .866 inches
width A = .981 inches
Style A: with sound (academy aperture)
Style B: with sound (anamorphic)
Style C: no sound (full ap)
November 14, 2006 SMPTE Meeting, Hollywood Section 12
Negative Film ScanningCineon (Kodak)
Quarter resolution - 2K context
width A = .866 inches
width A = .981 inches
Physical dimensions on film equal pixel counts in digital
1 pixel = .0004724 inches
220 pixels = sound track area
1828 pixels = .864 inches
2048 pixels = .968 inches
1920 pixels = HD
November 14, 2006 SMPTE Meeting, Hollywood Section 13
Projectable Image AreaSMPTE Standard 195 width A = .825 inches
1746 pixels = .825 inches
1956 pixels = .924 inches
The actual film image area that is projected may be smaller... keystoning (see note 2 in SMPTE 195)
Image area is intended for projection
Rest of film is intended for NOT projection
usually matches the
Ground Glass lines
November 14, 2006 SMPTE Meeting, Hollywood Section 14
SDI - Serial Digital InterfaceSMPTE Standards 292 and 372
for connecting equipment
• 4:2:2 is single link - 1.5 Gigabit / sec.• 4:4:4 is dual link - 3 Gigabit / sec.• HSDL is at half frame rate (not SMPTE)
A stream of pixels
10 bit Integer numbers (Code Values 4 - 1019)
November 14, 2006 SMPTE Meeting, Hollywood Section 15
4:4:4 or 4:2:24:4:4 is RGB or YCrCb
YCrCb is an intermediate format to and from RGB
4:4:4 YCrCb
4:2:2 interface
4:2:2 is always YCrCb
4:2:2, some of the pixels have no chroma– Chroma is sub-sampled
Y is luminance, a monochrome gray-scale
Cr and Cb are rectangular coordinates that identify the color
November 14, 2006 SMPTE Meeting, Hollywood Section 16
Motion Picture Camera Imaging Sensors
• Film• 3-chip• Bayer - mosaic• Color Striped• Foveon
November 14, 2006 SMPTE Meeting, Hollywood Section 17
FilmRandomly located photon sensors
(film grain, dye clouds)
Focal plane established for commonly used lenses
Pictures are from Kodak publications H-1 and H-188
Layers
Co-sited colors
November 14, 2006 SMPTE Meeting, Hollywood Section 18
3-ChipUniformly positioned
photon sensors
Focal Plane different than Film - therefore different lenses
Prism splits the light into colors – 3 paths onto 3 chips
Co-sited colors
Picture is derived from http://en.wikipedia.org/wiki/Dichroic_prism
TRICHROIC PRISM ASSEMBLY
November 14, 2006 SMPTE Meeting, Hollywood Section 19
Bayer PatternMosaic pattern of single
color photo-sites– 4K? Over-sampled
Single chip
Focal Plane can be the same as Film - use the same lenses
Not Co-sited colors– Bayer Post Processing to
RGB (de-mosaic)
RAW IMAGE SENSOR PATTERN
AFTER PROCESSING
November 14, 2006 SMPTE Meeting, Hollywood Section 20
Color-stripedStriped pattern of single
color photo-sites– 6K? Over-sampled
Single chip
Focal Plane can be the same as Film - use the same lenses
Not Co-sited colors– Processing to RGB
RAW IMAGE SENSOR PATTERN
AFTER PROCESSING
November 14, 2006 SMPTE Meeting, Hollywood Section 21
FoveonUniform pattern of photo-sites
– Placed at different layer depths
Single chip
Focal Plane could be the same as Film– Use the same lenses
Layers - Colors filtered in the silicon
Co-sited colors
Not currently used for motion picture cameras - (yet?)
November 14, 2006 SMPTE Meeting, Hollywood Section 22
Thank You
Thank you to Michael Will at Modern VideoFilm for helping with the pictures.
If the participant becomes aware of the technology, the dream is shattered.
– unknown
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