NPP: Coefficients for nppiWarpPerspective

[Ygrene]

I’m trying to use nppiWarpPerspective_8u_C1R on an image but I get NPP_COEFF_ERROR. Which I don’t understand, as I have computed my coefficients in MatLab and testes the transformation there, where it works perferctly. Does NPP expect some special normalization? Is there a difference between what MatLab calls a projective and NPP a perspective Transform?
I tried calculating the coefficients with nppiGetPerspectiveTransform but always get a size error, probably because I’m mishandling the quadrangle specification. It’s a [4][2] matrix, but I can’t find a documentation on how to use it. Is (0,0) top left or bottom left? Does it go from 0 to x_pixels-1?

Thanks for any help!

[melonakos]

I’m trying to use nppiWarpPerspective_8u_C1R on an image but I get NPP_COEFF_ERROR. Which I don’t understand, as I have computed my coefficients in MatLab and testes the transformation there, where it works perferctly. Does NPP expect some special normalization? Is there a difference between what MatLab calls a projective and NPP a perspective Transform?

I tried calculating the coefficients with nppiGetPerspectiveTransform but always get a size error, probably because I’m mishandling the quadrangle specification. It’s a [4][2] matrix, but I can’t find a documentation on how to use it. Is (0,0) top left or bottom left? Does it go from 0 to x_pixels-1?

Thanks for any help!

You might want to try Jacket’s Image Processing Library, which provides all of the NPP functions in MATLAB. Take a look here: http://wiki.accelereyes.com/wiki/index.php/Jacket_NPP