The distribution of the encrypted information at the output of an encoding system is of major concern. When the
encrypted information is conveyed to the final user, the finite size of the recording medium affects the quality of the
encoded information. In this case, we face possible information degradation when recovering. In the present contribution
we focus our attention on the finite size of the recorder medium in an actual experimental situation. In order to improve
the quality of the decrypted data, we study the role that both the scattering element size of the masks and the input object
size play in the encrypting system. Therefore, we analyze the optimal spatial distribution of the encoded information at
the output of a 4f encrypting system. We present examples that support our proposal.