Edge detection in the presence of speckle noise in barcode scanning systems

Emanuel Marom*, Saša Krešić-Jurić

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


Speckle noise is inherent to laser barcode scanners since barcodes are usually printed on diffusive surfaces which generate speckle when illuminated by spatially coherent beams. In this paper statistical properties of barcode signals corrupted by speckle noise are analyzed. We derive closed form expressions for the autocorrelation function and power spectral density of speckle noise for scanning beams with arbitrary field distributions. Since differentiation is often used for enhancement of barcode edges, we also analyze the properties of differentiated speckle noise. We derive estimates for signal-to-noise ratio when a laser beam scans over an edge. The random edge jitter in a barcode signal caused by speckle noise is also analyzed. The theory is illustrated by applying the results to Gaussian beams.

Original languageEnglish
Pages (from-to)382-387
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2003
EventSpeckle Metrology 2003 - Trondheim, Norway
Duration: 18 Jun 200320 Jun 2003


  • Barcode scanners
  • Power spectral density
  • Random edge jitter
  • Signal-to-noise ratio
  • Speckle noise


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