How Many Ways Can You Count Your Ks?

1. How Many Ways Can You Count Your Ks? Siegfried Heep Modern VideoFilm ASC / SMPTE Meeting, 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 SMPTE Meeting, Hollywood Section

3. What is a Pixel? Picture Element • Pixel Counts • Pixel Properties 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 = ? SMPTE Meeting, Hollywood Section

5. 2K or 4K 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 Pixel Counts 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 SMPTE Meeting, Hollywood Section

7. 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

8. Typical Pixel Properties HD D-Cinema SMPTE Meeting, Hollywood Section

9. Clear the palate with some nice fresh sorbet. SMPTE Meeting, Hollywood Section

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. Motion Picture Camera Imaging Sensors • Film • 3-chip • Bayer - mosaic • Color Striped • Foveon SMPTE Meeting, Hollywood Section

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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