Then, here comes the real question. The prerequisite for solving color difference is how to evaluate color difference. Why do you think there is a color difference, but he thinks there is no color difference? What is the standard? How to test?
There are generally two identification methods on the market today.
Use a light box. Look at the color difference between two pieces of cloth under a specific light source. The disadvantage of this method is that the same color looks the same under a certain light box, but it looks different when changing the light source.
Use a spectrophotometer to measure the color of the fabric itself, independent of the light source. If the color difference measured by a spectrophotometer is small, the color difference will be very small when viewed under any light source. Nowadays, spectrophotometers are also gradually replacing light boxes. Currently, Nike/Addias/Coats, etc. all use this method.