previous

 

Figure 6.

The color index (CI) tool in use. The user takes a photograph of a clean, shadow-free rock face and then uses the slider (lower left) to highlight the desired pixels in red or blue. (A) Determination of CI in a leucocratic granodiorite. The CI is displayed at upper right. A portion of the highlighted pixels has been erased to show the unhighlighted image below. (B) Using the CI tool for quick estimation of the percentage of porosity, as represented by blue epoxy, in a sandstone. The left half of the image is the original photomicrograph; on the right half the slider has been adjusted to highlight the epoxy. Dark inclusions represent ~3% of the image (as determined with the slider); thus, the porosity is 40%. Photomicrograph by Michael C. Rygel.

previous