int im_project(IMAGE *in, IMAGE *hout, IMAGE *vout)
The hout result image is 1 x in->Ysize pixels, where each pixel is the sum of all the pixels in that row of the input image. The vout result image is in->Xsize x 1 pixels, where each pixel is the sum of all the pixels in that column of the input image.
The output images are of the largest appropriate type for the input image: so unsigned integer images produce UINT output, and so on. The output images have the same number of bands as the input.
The operation does not work for complex images, or for coded images.