1. A process to make secure a personal portable object comprising a body of the personal portable object, a microchip, a printed image and a device to enable said personal portable object to communicate with an entity external to the device, the process comprising: using an image file comprising a stored image and an insertion algorithm to generate an image feature vector Vsi(num), wherein generating the image feature vector Vsi(num) comprises: dividing, for each division level of a plurality of division levels, the stored image into sub-images sized according to the division level to obtain a first plurality of sub-images corresponding to the plurality of division levels, wherein, for each division level, sub-images of the division level comprise a different number of pixels than sub-images of each other division level, and wherein, for each division level, at least one sub-image of the division level overlaps at least one sub-image of each other division level, selecting, from the first plurality of sub-images, a first selection of sub-images using a pseudo-random sequence, and combining data from the first selection of sub-images to generate Vsi(num); storing the image feature vector Vsi(num) in the microchip; using a read-back algorithm to match the image feature vector Vsi(num) and an image feature vector Vsi(dig) obtained using the printed image.