Dichroitic displays of (a) reflection and (b) transmission modes for the same PVA structures at 10% RH (dry state) and 100% RH (moist state), respectively. (c) Reflection spectra and corresponding color displays at the dry state (left) and the moist state (right). (d) Transmission spectra and corresponding color displays at the dry state (left) and the moist state (right).The initial H_PVA in the spectra of (c) and (d) are 129 nm, 130 nm, 143 nm, 147 nm, 160 nm, 164 nm and 169 nm, respectively.