Sigma points, similar to the TIC definition, refer to the sum of the four CMYK colors, but measured and analyzed specifically in Photoshop. An increase in sigma can lead to various problems. This color sum can be checked in Photoshop, but due to the time-consuming process, it's recommended to use Acrobat.
There are always areas in an image that consume a high concentration of ink. Therefore, during printing, these areas can damage the printing material, forcing the machine operator to adjust the ink density to save the material. Ultimately, this results in a color shift in the final packaging.
The resistance limit varies between different materials. Typically, a maximum of 350% is considered for glossy paper and 300% for plain paper. However, these values are only reliable under optimal production conditions. It is recommended to always choose an ink limit below these values.
- For flexible materials (like films), this limit varies depending on the color profile, Anilox or substrate.
The sigma level can be checked in Photoshop using the Info panel. After selecting the "Total Ink" option and moving the mouse over the image, you can check the sum of CMYK values and make adjustments if necessary.
