w w w

AIC Color 2001, Rochester, NY

Trends in color imaging on the Internet

Giordano Beretta

Hewlett-Packard Laboratories

Robert Buckley

Xerox Architecture Center

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

2User expectations

• Many users access the Internet in the office on fast workstations connected over fast links to the Internet

• Increasingly, private homes are equipped with fast connections over DSL, cable modem, satellite, …

• At home users often have fast graphics controllers for playing realistic computer games

• The latest video game machines are very powerful graphic workstations

• Today’s peripherals have “photo quality” color

These user experiences set very high expectations for color imaging on the Internet

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

3Polarization of devices

The nomadic workforce

• The new generation grew up on video games & WWW

• Expect concise answers immediately on multiple media

• The new working world is mobile and wireless

• a comprehensive fast fiber optics network provides a global backbone

• the “last mile” is wireless

• computers are wearable

• An appropriate viewing device has not yet been invented

• the content will be electronic

• the viewing conditions will be unpredictable

• likely, a plethora of viewing devices will be in use

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

4Problems raised by new trend

• How do we deal with unknown viewing conditions?

• How can we transmit images at very low bit rates?

• How can we retrieve images on the Internet?

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

5LCD display technology

• Cost falling faster than cost of CRT

• Mainstream also on desktop

• Most implementations different from CRT

• white point not on Planckian Locus

• sigmoidal tone reproduction curve

• greenish blue

• More brands with graphic arts specs

• Characterization only slightly more complex than CRT

• can apply ICC-based CMS

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

6Appearance mode

• CRT is darker than surroundings

• perceived as object in field of view

• viewing conditions must be controlled

• color fidelity is important

• LCD is brighter than surroundings

• similar to illuminator viewing condition

• visual system adapts to white point, memory colors

• Consistency principle (Evans)

• reproduction of relation among colors more important than absolute colorimetry

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

7JPEG 2000

• Adds many features that allow Internet users to interact with the compressed data in ways not supported by JPEG

• Achieves acceptable image quality at very low bit rates

• Wavelet based

• Can mimic foveation of human visual system

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

8Image compressed with JPEG

0.125 bpp

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

9Image compressed with JPEG 2000

0.125 bpp

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

10JPEG codestream is packetized

• First few packets are such that you can decompress and obtain an image with more quality in the ROI (face) than in the periphery (surround)

• As more packets arrive, you obtain the data to produce better quality in the surround, so that the entire image is rendered at the same quality

• User can truncate the process anywhere in between

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

11Image compressed with JPEG 2000

ROI coding (face)

equivalent to 0.125 bpp

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

12Image compressed with JPEG 2000

ROI coding

equivalent to 0.25 bpp

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

13Image compressed with JPEG 2000

ROI coding

equivalent to 0.5 bpp

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

14Image compressed with JPEG 2000

ROI coding

equivalent to 1 bpp

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

15Image compressed with JPEG 2000

ROI coding

equivalent to 2 bpp

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

16Image compressed with JPEG 2000

ROI coding

equivalent to 4 bpp

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

17Algorithms for ROI

• Human vision collects low resolution overview in the retina’s periphery

• High resolution views in the fovea with each fixation as the eye jumps from ROI to ROI under top-down control

L. Stark and C. Privitera, U.C. Berkeley & eFovea

3K bytes

3K bytes

ROIs

100K bytes

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

18Image retrieval

• Text-based image retrieval: images are annotated and a database management system is used to perform image retrieval on the annotation

• drawback 1: labor required to manually annotate the images

• drawback 2: imprecision in the annotation process

• Content-based image retrieval systems (CBIRS) overcome these problems by indexing the images according to their visual content, such as color, texture, etc.

A goal in CBIR research is to design representations that correlate well with the human visual system

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

19Rendered images

• Stock photo agency images are rendered to a normalized intent

• Typical consumer images are the raw output of digital cameras or scanners

• Many CBIR algorithms rely on color histograms

• Need to specify when images are unrendered

• RIMM/ROMM RGB

• Need algorithms to perform automatic rendering operation

R.R. Buckley & G.B. Beretta AIC Color 2001 Trends in color imaging on the Internet

20Conclusions

• At Color ‘97 in Kyoto we predicted the availability of cheap processing and fast cheap Internet

• compared compression in the color domain to compression in the spatial domain; file formats

• Today we see a trend towards bright LCD displays and wireless devices

• color consistency more important than fidelity

• packetized low bit rate codestreams with ROI

• contents based image retrieval

• At Color ‘05 we will see

• image-capable handheld devices with wireless Internet

• world-wide dop-down image search & retrieval from handheld

• incredibly bright handheld displays based on OLED