• journal_title：Geophysics
• Contributor：Frank J. Feagin
• Publisher：Society of Exploration Geophysicists
• Date：1981-
• Format：text/html
• Language：en
• Identifier：10.1190/1.1441182
• journal_abbrev：Geophysics
• issn：0016-8033
• volume：46
• issue：2
• firstpage：106
• section：Articles

Relatively little attention has been paid to the final output of today's sophisticated seismic data processing procedures--the seismic section display. We first examine significant factors relating to those displays and then describe a series of experiments that, by varying those factors, let us specify displays that maximize interpreters' abilities to detect reflections buried in random noise.The study:From psychology of perception and image enhancement literature and from our own research, these conclusions were reached: (1) Seismic reflection perceptibility is best for time scales in the neighborhood of 1.875 inches/sec because, for common seismic frequencies, the eye-brain spatial frequency response is a maximum near that value. (2) An optimized gray scale for variable density sections is nonlinearly related to digital data values on a plot tape. The nonlinearity is composed to two parts (a) that which compensates for nonlinearity inherent in human perception, and (b) the nonlinearity required to produce histogram equalization, a modern image enhancement technique.The experiments:The experiments involved 37 synthetic seismic sections composed of simple reflections embedded in filtered random noise. Reflection signal-to-noise (S/N) ratio was varied over a wide range, as were other display parameters, such as scale, plot mode, photographic density contrast, gray scale, and reflection dip angle. Twenty-nine interpreters took part in the experiments. The sections were presented, one at a time, to each interpreter; the interpreter then proceeded to mark all recognizable events.Marked events were checked against known data and errors recorded. Detectability thresholds in terms of S/N ratios were measured as a function of the various display parameters. Some of the more important conclusions are: (1) With our usual types of displays, interpreters can pick reflections about 6 or 7 dB below noise with a 50 percent probability. (2) Perceptibility varies from one person to another by 2.5 to 3.0 dB. (3) For displays with a 3.75 inch/sec scale and low contrast photographic paper (a common situation), variable density (VD) and variable area-wiggly trace (VA-WT) sections are about equally effective from a perceptibility standpoint. (4) However, for displays with small scales and for displays with higher contrast, variable density is significantly superior. A VD section with all parameters optimized shows about 8 dB perceptibility advantage over an optimized VA-WT section. (5) Detectability drops as dip angle increases. VD is slightly superior to VA-WT, even at large scales, for steep dip angles. (6) An interpreter gains typically about 2 dB by foreshortening, although there is a wide variation from one individual to another.