Method for noise-immune gradient detection of object contours on digital images

FIELD: information technology.

SUBSTANCE: position of pulse noise on the image is evaluated first, after which four auxiliary masks are formed, as well as eight control vectors (two vectors based on each auxiliary mask), and coefficients of corresponding four differently aligned Prewitt masks are then changed using given vectors. Further, the given masks are used to calculated the approximate value of the modulus of the image gradient, and contours of the object on the image are obtained through its threshold conversion.

EFFECT: higher sensitivity of the noise-immune gradient method of detecting contours to useful contour features of the image.

5 dwg

 

The text descriptions are given in facsimile form.

How robust gradient contours allocation of objects in digital grayscale images, which are pre operation assessment provisions of impulse noise on the image receiving binary matrix interference assessmentthe size of the image units which spatial indicate the coordinates of impulse noise in the image, and zeros for their absence, then, based on theform four auxiliary mask: Horiz is Stalnoy H1, vertical H2, main-H3 diagonal and side-H4 diagonal, as well as control vectors, which have the four differently oriented masks Prewitt (horizontal W1, vertical W2, the main-diagonal W3 and side-diagonal W4) of size 3×3 elements each, with which calculates an approximate value of the component of the gradient at each point of the image, and then determine the module of the gradient, and by the threshold of transformation, the new white matrix black allocate elements, the module of the gradient for which the corresponding image coordinates exceeds the threshold of transformation, characterized in that with the aim of increasing the sensitivity to the contour characteristics of the image in terms of impulse noise based on each of the auxiliary mask H1, H2, H3, H4, form two control vector:
(consisting of the top the row vector H1), and
(consisting of the lower the row vector H1 (W1),
(consisting of a left vector-column H2) and
(consisting of the right vector-column H2) (W2),(consisting of 3 elements H3, located to the left and below the main diagonal H3) and
(consisting of 3 elements H3, nah the way to the right and above the main diagonal N3) (W3),
(consisting of 3 elements N4, located to the left of and above the secondary diagonal N4) and(consisting of 3 elements H4 on the right side and below the secondary diagonal N4) (W4), then using V11 and V12, V21 and V22, V31, and V32, V41 and V42 are changing operation coefficients corresponding masks W1, W2, W3, W4 according to the following rule: if any one factor masks (i.e. all 3 of nonzero coefficients (mask Prewitt) of the same sign) when mask processing is mapped to multiply the pixel of the image, distorted by impulse noise (as indicated by the corresponding non-zero component vectors V11, V12, V21, V22, V31, V32, V41, V42, formed on the basis of)this ratio masks assign a value of zero, and the remaining coefficients masks multiply 1.5 times; if any two coefficients masks are mapped to multiply the pixels of the image, distorted by impulse interference, then these coefficients masks assign zero values, and the remaining coefficient is multiplied 3 times; if all three factors one of the two masked included in the mask, are mapped to the pixels of the image, distorted by impulse interference, all 6 of the mask coefficients assigned zero values.



 

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