Fixed the formulas, based on issue #2145

doc/tutorials/calib3d/camera_calibration/camera_calibration.rst

@@ -12,8 +12,8 @@ For the distortion OpenCV takes into account the radial and tangential factors.
 
 .. math:: 
 
-   x_{corrected} = x( 1 + k_1 r^2 + k_2 r^4 + k^3 r^6 \\
-   y_{corrected} = y( 1 + k_1 r^2 + k_2 r^4 + k^3 r^6
+   x_{corrected} = x( 1 + k_1 r^2 + k_2 r^4 + k^3 r^6) \\
+   y_{corrected} = y( 1 + k_1 r^2 + k_2 r^4 + k^3 r^6)
 
 So for an old pixel point at :math:`(x,y)` coordinate in the input image, for a corrected output image its position will be :math:`(x_{corrected} y_{corrected})` . The presence of the radial distortion manifests in form of the "barrel" or "fish-eye" effect. 
 
@@ -21,8 +21,8 @@ Tangential distortion occurs because the image taking lenses are not perfectly p
 
 .. math:: 
 
-   x_{corrected} = x + [ 2p_1y + p_2(r^2+2x^2)] \\
-   y_{corrected} = y + [ 2p_1(r^2+ 2y^2)+ 2p_2x]
+   x_{corrected} = x + [ 2p_1xy + p_2(r^2+2x^2)] \\
+   y_{corrected} = y + [ p_1(r^2+ 2y^2)+ 2p_2xy]
 
 So we have five distortion parameters, which in OpenCV are organized in a 5 column one row matrix: