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