The document summarizes the JPEG image compression standard developed in 1991. It describes the need for image compression as digital cameras became more common, and outlines the technologies of the time period. The key aspects of the JPEG standard are discussed, including the discrete cosine transform used for lossy compression, quantization that removes non-essential data, and entropy coding for storage. The standard has had massive impact, being used universally for digital image storage and online sharing, though it has some limitations for high-quality compression.

1. The
JPEG
S*ll
Picture
Compression
Standard
by
Gregory
K.
Wallace,
1991
Julià
Minguillón
Barcelona
Compsci
Club

2. Contents
• Why
a
talk
on
JPEG?
• Previous
to
JPEG
• Technology
at
that
Fme
• The
paper
• Math
foundaFons
• The
algorithms
• Impact
• Caveats
• Related
papers

3. Why
a
talk
on
JPEG?
• JPEG
images
are
everywhere!
– Facebook:
350000000
photos
uploaded
every
day
– Almost
1000000000000
photos
taken
every
year!
• 1995
capstone
project
at
UAB
– ImplementaFon
of
progressive
operaFon
modes
in
IJG
library
v6b
• Perfect
excuse
for
checking
over
Lena
again!

4. Lena
512
x
512
x
24bpp
hZp://sipi.usc.edu/database/?volume=misc

5. Previous
to
JPEG
• …
• TIFF
1986
• GIF
1987
• PBM
1991
• …
• Limited
compression
raFos
(lossless)
• No
standard
for
lossy
image
compression
• JPEG
commiZee
created
in
1986
(ISO
in
1983)

6. Technology
at
that
Fme
• 1991:
Kodak
DCS
100,
1.3MP,
200MB
HD,
only
987
sold
(aimed
at
photojournalists,
20000$)
• 1994:
Apple
QuickTake
100,
0.3MP
(VGA),
749$
• …
• Computers
in
1991:
Intel
486DX,
MS-­‐DOS
5.0,
Windows
3.0,
Linux,
VGA
(640x480x256
-­‐
yes,
Amiga
was
beZer!),
Adobe
Photoshop
2.0,
1st
color
image
scanner
(HP)

7. The
paper
Wallace,
G.K.
(1991).
The
JPEG
sFll
picture
compression
standard.
CommunicaFons
of
the
ACM
–
special
issue
on
digital
mulFmedia
systems,
34(4),
30-­‐44.
• Summary
of
JTC1/SC2/WG10
• Already
a
classic
(>
4500
cites)
hZp://www-­‐ee.eng.hawaii.edu/~treed/EE416/
Project_4/jpeg-­‐wallace.pdf

8. Math
foundaFons
• Lossy
compression
≈
remove
what
eye
can’t
see
• Karhunen-­‐Loève
transform:
any
stochasFc
process
can
be
decomposed
in
an
infinite
linear
combinaFon
of
orthogonal
funcFons
– Coefficients
are
decorrelated
– Any
truncaFon
minimizes
MSE
• Discrete
cosine
transform
– Similar
to
DFT
but
real
coefficients
– Existence
of
fast
/
reversible
/
integer
versions

9. The
algorithms
• Color
conversion
from
R-­‐G-­‐B
to
Y-­‐Cb-­‐Cr
• Sampling
and
interleaving
• DCT
• QuanFzaFon
(loss/compression
happens
here)
• Reordering
(zig-­‐zag
sequence)
• Entropy
coding:
zeros,
markers
• Symmetrical
process
for
coding
/
encoding

11. Impact
• All
devices
taking
pictures
implement
JPEG
• JPEG
File
Interchange
Format
(.jpg,
.jpeg)
• IJG
library
used
elsewhere
• Hardware
encoders
/
decoders
available
• Part
also
of
M-­‐JPEG
(prior
to
MPEG-­‐4)
• Superseded
by
JPEG2000
(but…)

12. Caveats
• 8
x
8
blocks
are
too
small
• “Limited”
to
12
bit
samples
• Bad
quality
for
high
compression
raFons
• ArithmeFc
coding
not
used
due
to
patents
• HVS
opFmizaFon
barely
used
• In
general,
most
devices/apps
do
not
allow
users
to
specify
all
JPEG
parameters
• Awful
results
if
wrongly
used
(text,
diagrams)

13. Related
papers
Rao,
K.R.,
Yip,
P.
(1990).
Discrete
Cosine
Transform
algorithms.
Advantages,
ApplicaFons.
Academic
Press,
Inc.
London.
Huffman,
D.A.
(1962).
A
method
for
the
construcFon
of
minimum
redundancy
codes.
In
Proceedings
of
the
IRE,
40,
1098-­‐1101.
Pennebaker,
W.B.,
Mitchell,
J.L.
(1993).
JPEG
SFll
image
data
compression
standard.
Van
Nostrand
Reinhold,
New
York.
Peterson,
H.A.,
Ahumada,
A.J.,
Watson,
A.B.
(1993).
An
Improved
DetecFon
Model
for
DCT
Coefficient
QuanFzaFon.
In
Human
Vision,
Visual
Processing,
and
Digital
Display
IV,
ed.
B.E.
Rogowitz
and
J.
Allebach,
Proc.
1913,
191-­‐201.
Minguillón,
J.,
Pujol,
J.
(2001).
JPEG
standard
uniform
quanFzaFon
error
modeling
with
applicaFons
to
sequenFal
and
progressive
operaFon
modes.
Journal
of
Electronic
Imaging,
10(2),
475-­‐485.