Abstract

In video-based particle-image velocimetry (PIV) systems for fluid mechanics research, it is sometimes desirable to image seed particles to be smaller than a camera pixel. However, imaging to this size can lead to marginal image contrast such that significant numbers of erroneous velocity vectors can be computed, even for simple flow fields. A variety of image-enhancement techniques suitable for a low-cost PIV system that uses video cameras are examined and tested on three representative flows. Techniques such as linear contrast enhancement and histogram hyperbolization are shown to have good potential for improving the image contrast and hence the accuracy of the data-reduction process with only a 15% increase in the computational time. Some other schemes that were examined appear to be of little practical value in PIV applications. An automated shifting algorithm based on mass conservation is shown to be useful for displacing the second interrogation region in the direction of flow, which minimizes the number of uncorrelated particle images that contribute noise to the data-reduction process.

© 2000 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. R. J. Adrian, “Multi-point optical measurements of simultaneous vectors in unsteady flow—a review,” Int. J. Heat Fluid Flow 7, 127–145 (1986).
    [CrossRef]
  2. Y. A. Hassan, O. G. Philip, W. D. Schmidt, “Bubble collapse velocity measurements using a particle image velocimetry technique with fluorescent tracers,” in Experimental and Numerical Flow Visualization (American Society of Mechanical Engineers, New York, 1993), 172, pp. 85–92.
  3. X. Zhang, C. S. Cox, “Feature correlation for particle image velocimetry: an application of pattern recognition,” in Optical Techniques in Fluid, Thermal, and Combustion Flows, S. S. Cha, J. Trolinger, eds., Proc. SPIE2546, 46–53 (1995).
    [CrossRef]
  4. M. P. Wernet, “Fuzzy inference enhanced information recovery from digital PIV using cross-correlation combined with particle tracking,” in Optical Techniques in Fluid, Thermal, and Combustion Flows, S. S. Cha, J. Trolinger, eds., Proc. SPIE2546, 54–64 (1995).
    [CrossRef]
  5. E. L. Hall, Computer Image Processing and Recognition (Academic, New York, 1979).
  6. E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
    [CrossRef]
  7. A. Rosenfeld, A. C. Kak, Digital Picture Processing (Academic, New York, 1982), Chap. 1.
  8. A. Mokrane, “A new image contrast enhancement technique based on a contrast discrimination model,” CVGIP Graph. Models Image Process. 54, 171–180 (1992).
    [CrossRef]
  9. W. Frei, “Image enhancement by histogram hyperbolization,” Comput. Graph. Image Process. 6, 286–294 (1977).
    [CrossRef]
  10. W. K. Pratt, Digital Image Processing (Wiley, New York, 1991).
  11. S. R. Pierce, “Fluid flow characterization by digital particle image velocimetry,” M.S. thesis (University of Wyoming, Laramie, Wyo., 1995).
  12. G. L. Switzer, L. P. Goss, D. D. Trump, B. Sarka, “Application of laser-sheet-lighting techniques to multiple-point velocity measurements in mixing flows,” in International Congress of on Application of Lasers and Electro-Optics (Laser Institute of America, Toledo, Ohio, 1986), 58, pp. 106–113.
  13. W. H. Press, B. P. Flannery, S. A. Teukolsky, W. T. Vetterling, Numerical Recipes in C, The Art of Scientific Computing (Cambridge U. Press, Cambridge, UK, 1988).
  14. J. Macharivilakathu, “Image processing techniques in particle image velocimetry,” M.S. thesis (University of Wyoming, Laramie, Wyo., 1998).
  15. A. M. Fincham, G. R. Spedding, “Low cost, high resolution DPIV for measurement of turbulent fluid flow,” Exp. Fluids 23, 449–462 (1997).
    [CrossRef]
  16. E. A. Cowen, S. G. Monismith, “A hybrid digital particle tracking velocimetry technique,” Exp. Fluids 22, 199–211 (1997).
    [CrossRef]
  17. J. P. Hartnett, C. Y. Koh, S. T. McComas, “A comparison of predicted and measured friction factors for turbulent flow through square ducts,” J. Heat Transfer 84, 82–88 (1962).
    [CrossRef]
  18. J. Laufer, “The structure of turbulence in fully developed pipe flow,” (National Advisory Committee for Aeronautics, Washington, DC, 1954).

1997

A. M. Fincham, G. R. Spedding, “Low cost, high resolution DPIV for measurement of turbulent fluid flow,” Exp. Fluids 23, 449–462 (1997).
[CrossRef]

E. A. Cowen, S. G. Monismith, “A hybrid digital particle tracking velocimetry technique,” Exp. Fluids 22, 199–211 (1997).
[CrossRef]

1992

A. Mokrane, “A new image contrast enhancement technique based on a contrast discrimination model,” CVGIP Graph. Models Image Process. 54, 171–180 (1992).
[CrossRef]

1986

R. J. Adrian, “Multi-point optical measurements of simultaneous vectors in unsteady flow—a review,” Int. J. Heat Fluid Flow 7, 127–145 (1986).
[CrossRef]

1977

W. Frei, “Image enhancement by histogram hyperbolization,” Comput. Graph. Image Process. 6, 286–294 (1977).
[CrossRef]

1971

E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
[CrossRef]

1962

J. P. Hartnett, C. Y. Koh, S. T. McComas, “A comparison of predicted and measured friction factors for turbulent flow through square ducts,” J. Heat Transfer 84, 82–88 (1962).
[CrossRef]

Adrian, R. J.

R. J. Adrian, “Multi-point optical measurements of simultaneous vectors in unsteady flow—a review,” Int. J. Heat Fluid Flow 7, 127–145 (1986).
[CrossRef]

Cowen, E. A.

E. A. Cowen, S. G. Monismith, “A hybrid digital particle tracking velocimetry technique,” Exp. Fluids 22, 199–211 (1997).
[CrossRef]

Cox, C. S.

X. Zhang, C. S. Cox, “Feature correlation for particle image velocimetry: an application of pattern recognition,” in Optical Techniques in Fluid, Thermal, and Combustion Flows, S. S. Cha, J. Trolinger, eds., Proc. SPIE2546, 46–53 (1995).
[CrossRef]

Dwyer, S. J.

E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
[CrossRef]

Fincham, A. M.

A. M. Fincham, G. R. Spedding, “Low cost, high resolution DPIV for measurement of turbulent fluid flow,” Exp. Fluids 23, 449–462 (1997).
[CrossRef]

Flannery, B. P.

W. H. Press, B. P. Flannery, S. A. Teukolsky, W. T. Vetterling, Numerical Recipes in C, The Art of Scientific Computing (Cambridge U. Press, Cambridge, UK, 1988).

Frei, W.

W. Frei, “Image enhancement by histogram hyperbolization,” Comput. Graph. Image Process. 6, 286–294 (1977).
[CrossRef]

Goss, L. P.

G. L. Switzer, L. P. Goss, D. D. Trump, B. Sarka, “Application of laser-sheet-lighting techniques to multiple-point velocity measurements in mixing flows,” in International Congress of on Application of Lasers and Electro-Optics (Laser Institute of America, Toledo, Ohio, 1986), 58, pp. 106–113.

Hall, D. L.

E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
[CrossRef]

Hall, E. L.

E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
[CrossRef]

E. L. Hall, Computer Image Processing and Recognition (Academic, New York, 1979).

Hartnett, J. P.

J. P. Hartnett, C. Y. Koh, S. T. McComas, “A comparison of predicted and measured friction factors for turbulent flow through square ducts,” J. Heat Transfer 84, 82–88 (1962).
[CrossRef]

Hassan, Y. A.

Y. A. Hassan, O. G. Philip, W. D. Schmidt, “Bubble collapse velocity measurements using a particle image velocimetry technique with fluorescent tracers,” in Experimental and Numerical Flow Visualization (American Society of Mechanical Engineers, New York, 1993), 172, pp. 85–92.

Koh, C. Y.

J. P. Hartnett, C. Y. Koh, S. T. McComas, “A comparison of predicted and measured friction factors for turbulent flow through square ducts,” J. Heat Transfer 84, 82–88 (1962).
[CrossRef]

Kruger, R. P.

E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
[CrossRef]

Laufer, J.

J. Laufer, “The structure of turbulence in fully developed pipe flow,” (National Advisory Committee for Aeronautics, Washington, DC, 1954).

Lodwick, G. S.

E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
[CrossRef]

Macharivilakathu, J.

J. Macharivilakathu, “Image processing techniques in particle image velocimetry,” M.S. thesis (University of Wyoming, Laramie, Wyo., 1998).

McComas, S. T.

J. P. Hartnett, C. Y. Koh, S. T. McComas, “A comparison of predicted and measured friction factors for turbulent flow through square ducts,” J. Heat Transfer 84, 82–88 (1962).
[CrossRef]

McLaren, R. W.

E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
[CrossRef]

Mokrane, A.

A. Mokrane, “A new image contrast enhancement technique based on a contrast discrimination model,” CVGIP Graph. Models Image Process. 54, 171–180 (1992).
[CrossRef]

Monismith, S. G.

E. A. Cowen, S. G. Monismith, “A hybrid digital particle tracking velocimetry technique,” Exp. Fluids 22, 199–211 (1997).
[CrossRef]

Philip, O. G.

Y. A. Hassan, O. G. Philip, W. D. Schmidt, “Bubble collapse velocity measurements using a particle image velocimetry technique with fluorescent tracers,” in Experimental and Numerical Flow Visualization (American Society of Mechanical Engineers, New York, 1993), 172, pp. 85–92.

Pierce, S. R.

S. R. Pierce, “Fluid flow characterization by digital particle image velocimetry,” M.S. thesis (University of Wyoming, Laramie, Wyo., 1995).

Pratt, W. K.

W. K. Pratt, Digital Image Processing (Wiley, New York, 1991).

Press, W. H.

W. H. Press, B. P. Flannery, S. A. Teukolsky, W. T. Vetterling, Numerical Recipes in C, The Art of Scientific Computing (Cambridge U. Press, Cambridge, UK, 1988).

Sarka, B.

G. L. Switzer, L. P. Goss, D. D. Trump, B. Sarka, “Application of laser-sheet-lighting techniques to multiple-point velocity measurements in mixing flows,” in International Congress of on Application of Lasers and Electro-Optics (Laser Institute of America, Toledo, Ohio, 1986), 58, pp. 106–113.

Schmidt, W. D.

Y. A. Hassan, O. G. Philip, W. D. Schmidt, “Bubble collapse velocity measurements using a particle image velocimetry technique with fluorescent tracers,” in Experimental and Numerical Flow Visualization (American Society of Mechanical Engineers, New York, 1993), 172, pp. 85–92.

Spedding, G. R.

A. M. Fincham, G. R. Spedding, “Low cost, high resolution DPIV for measurement of turbulent fluid flow,” Exp. Fluids 23, 449–462 (1997).
[CrossRef]

Switzer, G. L.

G. L. Switzer, L. P. Goss, D. D. Trump, B. Sarka, “Application of laser-sheet-lighting techniques to multiple-point velocity measurements in mixing flows,” in International Congress of on Application of Lasers and Electro-Optics (Laser Institute of America, Toledo, Ohio, 1986), 58, pp. 106–113.

Teukolsky, S. A.

W. H. Press, B. P. Flannery, S. A. Teukolsky, W. T. Vetterling, Numerical Recipes in C, The Art of Scientific Computing (Cambridge U. Press, Cambridge, UK, 1988).

Trump, D. D.

G. L. Switzer, L. P. Goss, D. D. Trump, B. Sarka, “Application of laser-sheet-lighting techniques to multiple-point velocity measurements in mixing flows,” in International Congress of on Application of Lasers and Electro-Optics (Laser Institute of America, Toledo, Ohio, 1986), 58, pp. 106–113.

Vetterling, W. T.

W. H. Press, B. P. Flannery, S. A. Teukolsky, W. T. Vetterling, Numerical Recipes in C, The Art of Scientific Computing (Cambridge U. Press, Cambridge, UK, 1988).

Wernet, M. P.

M. P. Wernet, “Fuzzy inference enhanced information recovery from digital PIV using cross-correlation combined with particle tracking,” in Optical Techniques in Fluid, Thermal, and Combustion Flows, S. S. Cha, J. Trolinger, eds., Proc. SPIE2546, 54–64 (1995).
[CrossRef]

Zhang, X.

X. Zhang, C. S. Cox, “Feature correlation for particle image velocimetry: an application of pattern recognition,” in Optical Techniques in Fluid, Thermal, and Combustion Flows, S. S. Cha, J. Trolinger, eds., Proc. SPIE2546, 46–53 (1995).
[CrossRef]

Comput. Graph. Image Process.

W. Frei, “Image enhancement by histogram hyperbolization,” Comput. Graph. Image Process. 6, 286–294 (1977).
[CrossRef]

CVGIP Graph. Models Image Process

A. Mokrane, “A new image contrast enhancement technique based on a contrast discrimination model,” CVGIP Graph. Models Image Process. 54, 171–180 (1992).
[CrossRef]

Exp. Fluids

A. M. Fincham, G. R. Spedding, “Low cost, high resolution DPIV for measurement of turbulent fluid flow,” Exp. Fluids 23, 449–462 (1997).
[CrossRef]

E. A. Cowen, S. G. Monismith, “A hybrid digital particle tracking velocimetry technique,” Exp. Fluids 22, 199–211 (1997).
[CrossRef]

IEEE Trans. Comput.

E. L. Hall, R. P. Kruger, S. J. Dwyer, D. L. Hall, R. W. McLaren, G. S. Lodwick, “A survey of preprocessing and feature extraction techniques for radiographic images,” IEEE Trans. Comput. 20, 1032–1044 (1971).
[CrossRef]

Int. J. Heat Fluid Flow

R. J. Adrian, “Multi-point optical measurements of simultaneous vectors in unsteady flow—a review,” Int. J. Heat Fluid Flow 7, 127–145 (1986).
[CrossRef]

J. Heat Transfer

J. P. Hartnett, C. Y. Koh, S. T. McComas, “A comparison of predicted and measured friction factors for turbulent flow through square ducts,” J. Heat Transfer 84, 82–88 (1962).
[CrossRef]

Other

J. Laufer, “The structure of turbulence in fully developed pipe flow,” (National Advisory Committee for Aeronautics, Washington, DC, 1954).

A. Rosenfeld, A. C. Kak, Digital Picture Processing (Academic, New York, 1982), Chap. 1.

Y. A. Hassan, O. G. Philip, W. D. Schmidt, “Bubble collapse velocity measurements using a particle image velocimetry technique with fluorescent tracers,” in Experimental and Numerical Flow Visualization (American Society of Mechanical Engineers, New York, 1993), 172, pp. 85–92.

X. Zhang, C. S. Cox, “Feature correlation for particle image velocimetry: an application of pattern recognition,” in Optical Techniques in Fluid, Thermal, and Combustion Flows, S. S. Cha, J. Trolinger, eds., Proc. SPIE2546, 46–53 (1995).
[CrossRef]

M. P. Wernet, “Fuzzy inference enhanced information recovery from digital PIV using cross-correlation combined with particle tracking,” in Optical Techniques in Fluid, Thermal, and Combustion Flows, S. S. Cha, J. Trolinger, eds., Proc. SPIE2546, 54–64 (1995).
[CrossRef]

E. L. Hall, Computer Image Processing and Recognition (Academic, New York, 1979).

W. K. Pratt, Digital Image Processing (Wiley, New York, 1991).

S. R. Pierce, “Fluid flow characterization by digital particle image velocimetry,” M.S. thesis (University of Wyoming, Laramie, Wyo., 1995).

G. L. Switzer, L. P. Goss, D. D. Trump, B. Sarka, “Application of laser-sheet-lighting techniques to multiple-point velocity measurements in mixing flows,” in International Congress of on Application of Lasers and Electro-Optics (Laser Institute of America, Toledo, Ohio, 1986), 58, pp. 106–113.

W. H. Press, B. P. Flannery, S. A. Teukolsky, W. T. Vetterling, Numerical Recipes in C, The Art of Scientific Computing (Cambridge U. Press, Cambridge, UK, 1988).

J. Macharivilakathu, “Image processing techniques in particle image velocimetry,” M.S. thesis (University of Wyoming, Laramie, Wyo., 1998).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (14)

Fig. 1
Fig. 1

Image histograms of high-contrast paper masks.

Fig. 2
Fig. 2

(a) Experimental and (b) analytical flow fields for solid-body rotation, showing 14% erroneous vectors.

Fig. 3
Fig. 3

System accuracy as a function of seed density.

Fig. 4
Fig. 4

Unmodified histogram for solid-body rotation flow.

Fig. 5
Fig. 5

Comparison of performance of thresholding algorithms.

Fig. 6
Fig. 6

Performance of piecewise-linear contrast enhancement.

Fig. 7
Fig. 7

Performance of the histogram equalization technique.

Fig. 8
Fig. 8

Histogram of the hyperbolized image.

Fig. 9
Fig. 9

Performance of the histogram hyperbolization method.

Fig. 10
Fig. 10

Application of the shifting algorithm.

Fig. 11
Fig. 11

Measured flow field for solid-body rotation after use of shifting and histogram equalization algorithms.

Fig. 12
Fig. 12

Analytical and measured velocity profiles for laminar flow (Re = 560). Bars represent the extreme variation of velocities from those measured at 12 streamwise locations.

Fig. 13
Fig. 13

Mean velocity profile for turbulent flow.

Fig. 14
Fig. 14

rms velocities when the histogram is clipped at ±σ about the mean.

Tables (3)

Tables Icon

Table 1 Comparison of Various Image-Processing Techniques at Low Seed Densities for Solid-Body Rotation Flow Fields

Tables Icon

Table 2 Comparison of Image-Processing Techniques for a Flow in a Square Duct

Tables Icon

Table 3 Effects of Image-Processing Techniques on Time-Averaged Turbulent Flow in a Square Duct

Equations (18)

Equations on this page are rendered with MathJax. Learn more.

m<n<fx, y<N<M,
gx, y=hfx, y.
gx, y=fx, y-nN-nM-m+m;
Cx, y=-- fμ, vgμ+x, v+y*dμdv,
Cm, n=i=-j=- fi, jgi+m, j+n*.
f*g=-- fμ, vgμ-x, v-ydμdv.
Cx, y=f*g*;
f*g=-1FG,
Cx, y=-1FG*.
T=m+kσ,
hf=0  fT1=expαlogf-logT1+βα=log 255/logT2-log T1;β=0 T1fT2=255  fT2.
gk=hfj.
 Pf=1,   Pg=1.
n=1j Pf=m=1k Pg.
Pg=1/gmax-gmin,
hf=gmax-gminn=1j Pf+gmin.
Pg=1gloggmax-loggmin,
hf=gmingmaxgminm=1j Pf.

Metrics