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Determination of geometric deformations
in image registration using geometric and radiometric
measurements
Fevzi Karsli*
and Mustafa Dihkan
Department of Geomatics, Engineering Faculty,
Karadeniz Technical
University, 61080 Trabzon, Turkey.
*Corresponding author. E-mail:
fkarsli@ktu.edu.tr.
Tel: +90 462 3772769.
Fax: +90 462 3250918.
Accepted 12 January, 2010 |
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This paper presents a unified method based on pixels for
identifying the geometric deformations of digital images.
This method uses radiometric pixel gray values to represent
the geometric deformations over the entire image surface, a
test plate with a 38 × 22 grid,
along x and y
directions.
This method
uses a test plate to measure the radiometric pixel gray
values in images which represent the geometric deformations
in the image.
For image
registration and the detection of the geometric deformations
the following
six
geometric transformation methods were utilized;
non-reflective similarity, similarity, affine, projective,
polynomial, piecewise linear and three resampling methods;
nearest neighbour, bilinear and bicubic were used. The image
data were taken by using Olympus E-150 digital SLR camera
and the applied geometric transformation and resampling
methods were coded in Matlab software. The
experimental results of all the methods are presented and
evaluated. The results showed that non-reflective
similarity, similarity and affine transformations have a
better accuracy than the other methods. Furthermore,
geometric distortions were calculated by using corresponding
grid corners of pixel coordinates in normal and registered
images. Among all geometric transformation, projective
transformation combined with three resampling methods
revealed the best results.
Key words:
Digital image, transformation, geometric deformations,
registration, resampling. |
