1. A method for processing an input image securely, comprising: acquiring, in a client, an input image I; generating a set of m random images, H 1 ,. .. , H m , and a coefficient vector, a=[a 1 ,. .. , a m ], such that the input image I is I=Σ i=j m α i H j ; transferring the set of the random images to a server including a weak classifier; determining, in the server, a set of m convolved random mages H′, such that {H 1 ′=π 1 (H 1 *y} i.1 m , where * is the convolution operator and π 1 is a first random pixel permutation; transferring the set of convolved images to the client; determining, in the client, a set of m permuted image I′, such that I′=π 2 (Σ i=1 m α i H 1 ′), where π 2 is a second random pixel permutation; transferring the set of permuted image to the server; determining, in the server, a test image {overscore (I)} such that {overscore (I)}=α∫(I′); and returning a true signal to the client if there exist a pixel q in the test image such that {overscore (I)}(q)>0, otherwise return a false signal to the client to indicate whether or not the input image contains an object.