How Many Ways Can You Count Your Ks?

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# How Many Ways Can You Count Your Ks? - PowerPoint PPT Presentation

How Many Ways Can You Count Your Ks?. Siegfried Heep Modern VideoFilm ASC / SMPTE Meeting, November 14, 2006. 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

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### How Many Ways Can You Count Your Ks?

Siegfried Heep

Modern VideoFilm

ASC / SMPTE Meeting, November 14, 2006

SMPTE Meeting, Hollywood Section

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

SMPTE Meeting, Hollywood Section

What is a Pixel?

Picture Element

• Pixel Counts
• Pixel Properties

SMPTE Meeting, Hollywood Section

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 = ?

SMPTE Meeting, Hollywood Section

2K or 4K

2048 pixels wide

4096 pixels wide

3 vs. 12 Mega pixels

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

Pixel Counts

SMPTE Meeting, Hollywood Section

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

SMPTE Meeting, Hollywood Section

Examples of changing settings

low high

clipped applied twice

GAMMA CURVE

VIDEO LEVEL SCALING

Picture is derived from NIST test frame

SMPTE Meeting, Hollywood Section

Typical Pixel Properties

HD

D-Cinema

SMPTE Meeting, Hollywood Section

Clear the palate with some nice fresh sorbet.

SMPTE Meeting, Hollywood Section

DPX File Format, Digital Frame

SMPTE 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)

SMPTE Meeting, Hollywood Section

Film Camera Apertures

width A = .866 inches

SMPTE Standard 59

physical dimensions on film

• Style A: with sound (academy aperture)
• Style B: with sound (anamorphic)
• Style C: no sound (full ap)

width A = .981 inches

SMPTE Meeting, Hollywood Section

Negative Film Scanning

width A = .866 inches

Cineon (Kodak)

Quarter resolution - 2K context

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

width A = .981 inches

SMPTE Meeting, Hollywood Section

Projectable Image Area

width A = .825 inches

usually matches the

Ground Glass lines

SMPTE Standard 195

Image area is intended for projection

Rest of film is intended for NOT projection

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)

SMPTE Meeting, Hollywood Section

SDI - Serial Digital Interface

SMPTE 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)

SMPTE Meeting, Hollywood Section

4:4:4 or 4:2:2

4:4:4 is RGB or YCrCb

YCrCb is an intermediate format to and from RGB

Y is luminance, a monochrome gray-scale

Cr and Cb are rectangular coordinates that identify the color

4:4:4 YCrCb

• 4:2:2 is always YCrCb
• 4:2:2, some of the pixels have no chroma
• Chroma is sub-sampled

4:2:2 interface

SMPTE Meeting, Hollywood Section

Motion Picture Camera Imaging Sensors
• Film
• 3-chip
• Bayer - mosaic
• Color Striped
• Foveon

SMPTE Meeting, Hollywood Section

Film

Randomly located photon sensors (film grain, dye clouds)

Focal plane established for commonly used lenses

Layers

Co-sited colors

Pictures are from Kodak publications H-1 and H-188

SMPTE Meeting, Hollywood Section

3-Chip

Uniformly 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

TRICHROIC PRISM ASSEMBLY

Picture is derived from http://en.wikipedia.org/wiki/Dichroic_prism

SMPTE Meeting, Hollywood Section

Bayer Pattern

Mosaic 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

SMPTE Meeting, Hollywood Section

Color-striped

Striped 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

SMPTE Meeting, Hollywood Section

Foveon

Uniform 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?)

SMPTE Meeting, Hollywood Section

If the participant becomes aware of the technology, the dream is shattered.Thank You
• unknown

Thank you to Michael Will at Modern VideoFilm for helping with the pictures.

SMPTE Meeting, Hollywood Section