| Abstract: | Picture processing using generalized instrumentation with specially developed software, and image analysis by means of a Quantimet 720 image analyser with a linear correlator, were employed in the study of rock textures. The boundaries of all individual grains from a portion of a thin section of a rock were distinguished and hand-drafted for digitization and analysis. From the grey level image of boundaries of the profiles of the grains, obtained by hexagonal scanning of line drawings, binary images were produced for each phase and used for textural measurements. Ink drawings extracted from the boundary pattern were also used for the image analyser experiments. In picture processing experiments, programmed structuring elements of different shapes and two-dimensional autocorrelation functions were used to characterize morphology and spatial distribution of the different phases. Transformations of binary images were programmed at the bit level to reduce storage requirements and computing time. In Quantimet 720 experiments, linear erosion and histogram of sizes were used for computing the mean dimensions of the grains. Periodical arrangements were studied by means of the covariance function. This contribution uses simple texture measures derived from mathematical morphology and picture processing methods, in order to assess the feasibility of two different technical approaches in the analysis of the same material. The extraction of image information from the material analysed, which was not attempted before, is cumbersome and technically complex. This difficulty is partly responsible of why little is known on the quantitative characterization of metamorphic textures from thin sections. |
