The ISO 1 2625-7: 2021 standard specifies a method for measuring luminance and chroma of tissue and tissue paper products using a D65/10 ° Light source. The standard provides procedures for testing Optical inspection properties under simulated outdoor daylight conditions to help evaluate the visual performance of paper. By measuring luminance and chroma, users can understand the appearance mass of paper and compare and control products. The standard ensures the conformity and accuracy of measurement results, providing a scientific basis for the production and mass evaluation of paper.