Digital Cinema From Motion JPEG to Film projection A presentation by: Maxime Cassan Florent Rioult Neil Sinclair December 2008

Introduction Very recent technology Bits and bytes Use of digital technology for: ProductionDistributionProjection

Brief History of Digital Cinema 1999: First public demonstrations of modern day digital cinema 2002: Introducing security (Star Wars II) 2002: Creation of DCI 2005: Release of DCI specifications v : 6000 digital cinemas over the world (<2% of the total number of movie theaters)

Digital films: big computer files In the past: Numeric tapes DVDs Nowadays: HDDs only Distribution of digital films Immaterial distribution

Costs of Digital Cinema Single film print: $ GB HDD: $70 Reduced costs while shooting and editing Downsides: –Up to $ per screen –Digital playback system can cost 4 times as much as a film projector

Compression Compression Requirements: –Scalability –Camera Compression –Archive Compression –Compression Efficiency –Cost

What is Motion JPEG2000 Motion JPEG2000 is used in applications that require scalability, high quality, lossless coding and error resilience. Created as an advancement to JPEG and JPEG2000. Does not involve inter-frame encoding, only intra-frame encoding as each frame is encoded separately.

Scalability Resolution Example of resolution progressive bit streaming – [1] Quality Example of layer progressive bit stream ordering – [2] The left is bpp and the right is 0.5 bpp.

Intra-frame Encoding Each frame is independent Each image in the sequence is an exact representation of the data at every point in time due to the lossless coding Higher compression efficiency

Review of compression Flexible file format Scalability High compression High quality Lossless and near lossless compression Ideal for Digital Cinema

3 LCD Technology. White Light is separated in 3 beams: Red, Green, Blue. Each beam is masked by a LCD panel then the beams are recombined. Not used in Digital Cinema. Liquid Cristal Display Image from

The DLP is based on the Digital Micromirror Device (DMD) technology Each pixel is a tiny mirror which can be tilt: –In direction of the lens: the pixel is ON and white. –Away from the lens: the pixel is OFF and black DMD is used to modulate light intensity to obtain different shades of gray (1024). This is possible by tilting ON and OFF the mirror at a very high speed. Digital Micromirror Device Image from

The One chip DLP projector uses a chromatic wheel to filter the light to have successive Red, Green and Blue beams. The DMD is used to modulate light intensity of each pixel for each color beam. The HVS then merge the successive monochromatic images to form one full spectrum color image. The issue with the one chip system is the rainbow effect Digital Light Processing (One chip) Image from

One Chip DLP Rainbow Effect Photo taken of a hand moving quickly past a DLP projection, demonstrating the rainbow effect of a DLP projector's colour wheel. Author: Damien Donnelly From License: Creative Commons

The Three chip DLP projector uses a prism to create simultaneous Red, Green and Blue beams. Each one of those beam is reflected on a dedicated DMD On the way back from the DMD the three beam go through the prism one again to be merge into one single beam The is no rainbow effect with this system Digital Light Processing (Three chips) Image from

It is very similar to DLP as it is a reflective technology. Instead of using micromirror it uses liquid crystal. Liquid Crystal on Silicon Images from

Technology Comparison Own image from data on

Conclusion Is digital really better than film? –Clarity –Detail –Immune to: Scratches Fading Jitter –Total fidelity at every screening

Questions?