***.azi azimuth image
***.err error image (dark = high error)
CIP calculates a large number of image files, some of which are saved, others, the so-called primary results images, are discarded (they could be saved if need be). For all of these files, names have to be provided in the ***.ctrl file.
For each pixel CIP determines the discrete G(r) function (18 values), and determines the the exact maximum and minimum values and the corresponding angles of this curve by performing a parabolic fit to the five largest and smallest values. The error is given by the sum of all differences of the actual values to the ideal fit (see dialogue). For a given pixel coordinate the grey value of the different channels (images) are displayed (before and after calibration) and a curve fit is calculated:
VIEWPIX: X,Y coordinates > 200,200 (optional) ROT: 65 91 121 155 182 200 212 216 215 204 189 163 131 100 73 53 43 48 TILT: 47 46 47 46 -> MAX,MIN VALUE: 217 44 -> MAX,MIN PHASE: 81 171 -> SUM OF DIFF. : 119
Subtracting the minimum image from the maximum image yields the amplitude image. The phase image defined by the angle of the maximum at each pixel. The error image is defined by the sum of differences image. A primary azimuth and inclination image are derived from the phase and amplitude images. A second version for the primary inclination image is derived from the circular polarization image.
By comparing the grey values of the tilt images with the grey values in the ***.180 (=***.000) image, the tilt-correction is effected. This correction determines if a c-axis points above or below the plane of the thin section, and the inclination images are corrected accordingly. Finally the true azimuth and inclination images are derived and saved: ***.inca denotes the inclination derived from the amplitude of the G(r) curve, ***.incp denotes the inclination derived from the circular polarization image, ***.err denotes the error image.
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***.azi azimuth image |
***.err error image (dark = high error) |
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***.inca inclination by amplitude |
***.incp inclination by circular polarization |
The c-axis orientation image (denoted bei ***.coi) visualizes the orientation of the c-axis by assigning unique colours to different orientations.
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***.coi-CIP |
& CLUT |
The misorientation of the c-axis of a given pixel with respect to a reference direction is calculated and displayed as a grey value (0 ... 90). ***.misN, ***.misE, ***.misH, and ***.misR denote misorientations with respect to North, East, Heaven and reference direction (see ***.ctrl file and dialogue).
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***.misN (North) |
***.misE (East) |
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***.misH (Heaven) |
***.mis-45-90 (diagonal in plane of thin section) |
The local variation of c-axis orientation is obtained by gradient filtering: the angular differences of the c-axis of each pixel with respect to its 4 neighbouring pixels are calculated and added. ***.edga and ***.edgp denote that the inclinations from the ***.inca and ***.incp files have been taken.
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***.edga (using ***.inca) |
***.edgp (using ***.incp) |
From the azimuth and inclination images, histograms (***.cpf (calculated pole figure) = polar density matrix) are derived and stored follwing the conventions of MENTEX (ODF program). INVPIMA converts the ***.cpf file to a circular pole figure, ***.polfig (36·36), using the Schmidt projection. NIH Image and Lazy pole can be used to magnify the matrix and perform a contour shading.
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***.polfig (from CIP) |
***.polfig*5 (after Lazy grain boundary) |
