Coding techniques for
digital cinema
Andreja Samčović
University of Belgrade
Faculty of Transport and Traffic Engineering
Introduction
Film is the best presentation format for cinema content
Film is already being replaced by digitally content
Archives worldwide - to ingest, store, manage, conserve,
access and preserve efficiently film content in digital
form
Easy and economical access to digital version
Digital cinema (DC) intends to meet these requirements
Best quality and uncomplicated access to the stored
items
Digital Cinema Initiatives
In recent years, digital multimedia devices
become more and more popular in people’s daily
life
With the development of digital technology,
digital cinema has been putting into practice
Digital cinema is a new kind of application for
super high definition video
To establish an industrial standard for digital
cinema, a joint venture of 7 major Hollywood
studios, Digital Cinema Initiatives (DCI), founded
in March 2002, and put forward specification in
2005
Digital Cinema Initiatives
The DCI (Digital Cinema Initiative) specification
published in 2005 has selected JPEG2000 instead of
H.264 as the video coding standard for digital cinema
It shows that JPEG2000 has a better performance in the
field of super high definition video coding
Until now, only a few basic tests have been done to
compare between JPEG2000 and H.264 coding
standards
Moreover, the test resolutions and characteristics of
input sequences are very limited
JPEG2000 and H.264 are the latest image and video
coding standards, respectively
JPEG 2000
JPEG 2000 standard
Material eXchange Format
Open Archival Information System (OAIS) reference
model - own system architecture
Commercial archives - stock-shot licensing
companies, newsreel and future collections,
producers, and distributors
Public film archives - digitally projected cinema,
home video and home cinema, internet and
television distribution
File formats
Two different file formats to store image, audio and
metadata
Each is able to store archived items in the best
possible quality and to facilitate the access to the
archived items
Set of “modules”, produced at different places and
for different purposes
To create new metadata modules for different stuff,
people and deals
JPEG-2000 coding technique
JPEG-2000
Low-complexity standards for lossless image
compression do not permit a control of the resulting bitrate
This is possible by using the wavelet based standard
JPEG-2000, which allows for an embedded output bit
stream that can be truncated at a desired quality level
The drawback is increased complexity and a slightly
worse performance for mathematically lossless
compression
JPEG-2000 is based upon a wavelet decomposition of
the original image, with up to 5 wavelet decomposition
levels
JPEG-2000 coding technique
Each subband is divided into rectangular code-blocks,
and each code-block is independently coded by an
arithmetic codec using progressive bit planes
The bit stream is created by using a sophisticated
distortion minimization algorithm called EBCOT which
gives, for each layer, the optimum contribution of each
code block
Reversible wavelet transforms were used, and the
optional quantization was skipped
An intensive simulation campaign showed that no
appreciable gain is seen after the second wavelet level,
and this level was taken as a reference
We finally noted that colour space conversions (RGB,
YUV, YCbCr, etc.) do not give any appreciable gain, so
that images were compressed directly in their original
colour space
Standardization for archival
applications
The requirements for archival applications:
open standard (ISO standard 15444-1: 2004)
allows mathematically lossless as well as visually
lossless compression
advantage of allowing a scalable presentation of
image data
compression is performed on an intraframe basis
only
the use of wavelets and arithmetic entropy coding
produces a hierarchical code stream, allowing to
encode images at the desired maximum resolution
Standardization for archival
applications
RATE
CONTROL
RGB to
YCbCr
TRANSFORM
WAVELET
TRANSFORM
QUANTIZATION
ENTROPY
CODING
PACKETIZATION
FINAL
CODING
STREAM
Figure 2. General encoding
structure for JPEG 2000
Standardization for archival
applications
Wavelet-based image compression standard
To transform each colour component into a hierarchy
of subbands
Embedded block coding with optimized truncation
(EBCOT)
Context-adaptive arithmetic coding to
represent a collection of binary symbols
efficiently
Bit rate and quality are the two primary optimization
criteria for rate-control
Simulation results
Digital cinema is different in several fundamental ways
from other applications
The resolution is higher, with a single frame of 4x103
data containing approximately 8x106 pixels
The quality requirements are more stringent
Cinema viewers tend to sit within 1,5 to 3 screen
heights of the projected image
Relative compression efficiency advantages for coding
of digital cinema image sequences using JPEG 2000
and H.264 standards
Simulation results
The test content used was from the DCI (Digital
Cinema Initiatives) minimovie sequence “Confetti Title
Screen”
Resolution of 4096x1714 (sequence 4K), with 12 bits
per colour and 4:4:4 colour sampling
To reduce the amount of processing during the
experiment,
cropped region of size 512x208
(sequence 512) was used

a) JPEG 2000;

b) H.264 in which every frame is an I frame;

c) H.264 with an I frame of period 16, and with both B and P
frames used between the I frames
Simulation results
Figure 3. PSNR versus bit rate for 4K sequence
Simulation results
Figure 4. PSNR versus bit rate for 512 sequence
Conclusion
Film is being replaced by digitally content and this
lacks film’s noise affordable and more certain future
Practical solution - a system ready to be implemented
and as an overall approach and model
DC archive system is in its implementation phase
To meet the needs of archiving and distributing both
archival content and current digital productions
Digitized analogue film and video, digital video and
digital cinema products - to transcode them on demand
for distribution