Printing will inevitably have color difference. The color of printed matter is related to the influence of ink, machine, material, weather and other factors. Even if the same document is printed in the same batch or in different batches, the color difference is normal within plus or minus 15% of the filling color of the document. Because the printed matter is CMYK filled, the mobile phone or computer screen display is RGB, and the screen display color cannot be used as the reference color of the printed matter, because the standard CMYK chromatogram is used as the reference.