Image Processing Reference
In-Depth Information
In drawing there are maxima at values of rotating angle with added 90º multiples.. At
transition from a corner 89º to a corner 90º occurrence of maxima in a peak spectrum is
observed. Similar change of character of a peak spectrum gives a possibility to establish
value of a image rotation degree.
(а) (b)
Fig. 4. Spectrums of the projections corresponding to angles 89º and 90º (a-b) for 1024x1024
pixels image fragment
Result (an average of a spectrum for the Radon-transformed image for projection angles
from 0 º to 360 º with 10 º step) is presented in figure 5 and a dissection of it — an average of
Radon projection spectrograms for image fragment 1024x1024 pixels in figure 5. Local
maximums at 10 º , 100 º , 190 º , 280 º in figure 6 correspond diagonally-placed maximums in
figure 6. To determine the influence of image size change (resize operation), defined as the
relation of the linear sizes of the initial image to resulted one on possibility of rotation
detection by Radon transform, different scales of original image has also been investigated.
Fig. 5. An average of a spectrum of capacity of transformation of Radon (corners from 0º to
360º) at corners of turn from 0º to 360º with step 10º
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