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

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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?

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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