IEEE Transactions on Image Processing,
vol. 14, no. 12, pp. 1977-1989, Dec. 2005.
Hardcopy Image Barcodes Via Block Error Diffusion
Jonathan Yen (1),
Vishal Monga (2), and
Brian L. Evans (2)
(1) Halftoning and Image Processing Group,
1501 Page Mill Road,
Palo Alto, CA 94304
(2) Department of Electrical and Computer Engineering,
Engineering Science Building,
The University of Texas at Austin,
Austin, TX 78712-1084 USA
at UT Austin
Error diffusion halftoning is a popular method of producing
frequency modulated (FM) halftones for printing and display.
FM halftoning fixes the dot size (e.g. to one pixel
in conventional error diffusion), and varies the dot frequency
according to the intensity of the original grayscale image.
We generalize error diffusion to produce FM halftones with
user-controlled dot size and shape by using block quantization and
As a key application, we show how block error diffusion may be
applied to embed information in hardcopy using dot shape modulation.
We enable the encoding and subsequent decoding of information
embedded in the hardcopy version of continuous-tone base-images.
The encoding-decoding process is modeled by robust data transmission
through a noisy print-scan channel that is explicitly modeled.
We refer to the encoded printed version as an image barcode due to
its high information capacity that differentiates it from common
The encoding/halftoning strategy is based on a modified version of
block error diffusion.
Encoder stability, image quality vs. information capacity tradeoffs,
and decoding issues with and without explicit knowledge of the base-image
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