title: Accelerate's vImage vs. vDSP
body: <p>I'm trying to use the Accelerate framework on iOS to bypass the fact that Core Image on iOS doesn't support custom filters/kernels. I'm developing an edge detection filter using two convolutions with a <a href="http://en.wikipedia.org/wiki/Sobel_operator" rel="nofollow">Sobel kernel</a>, but starting with a simple Gaussian blur to get the hangs of it. I know vImage is geared towards image manipulation as matrices and vDSP focuses in processing digital signals using Fourier transforms. But although I started using the vImage functions (vImageConvolve_XXXX, etc), I'm hearing a lot of people discussing the use of vDSP's functions (vDSP_conv, vDSP_imgfir, etc) to do such things as convolutions. So that leads me to the question at hand: when should I use one over the other? What are the differences between them with regards to convolution operations? I've looked everywhere but couldn't find a clear answer. Can someone shed some lights on it, or point me in the right direction?</p>
  
  <p>Thanks!</p>