The ISO 1 2625-7: 2021 standard specifies the test method for the measurement of luminance and chroma of tissue paper and toilet paper under outdoor daylight conditions (D65/10 °). The standard details how to use the specified instrument and Light source (D65) to measure the Optical inspection characteristics of paper, including the values of luminance (L *), red-green axis (a *) and yellow-blue axis (b *). These parameters reflect the Color characteristics and visual effects of paper and are important for paper quality control and product comparison. The standard specifies the test conditions and equipment requirements to ensure the conformity and accuracy of the measurement results. Unlike the Measuring method in indoor light conditions (such as ISO 1 2625-15), this standard focuses on testing in outdoor daylight conditions to provide more informative Optical inspection data.