Principles and Precautions for Flexographic Image Adjustment

a. Be aware of highlight dropout.

b. Use complementary (opposite) colors carefully — it’s best to use only one complementary color if possible.

c. Ensure the total ink coverage does not exceed the paper’s ink absorption capacity.

1. Application of spot colors
   The use of spot colors should be analyzed on a case-by-case basis, depending on the design, materials, and printing conditions.
2. Registration mark positioning
   The position of registration marks should be carefully considered. Placing them too close to the edge can lead to alignment deviation.
   When a spot color plate includes both halftone and solid areas, consult the press operator to determine whether it is better to print them together on one plate or separately.
3. Handling fine elements
   Small text, thin lines, and multi-color registration areas require extra attention.
   Large solid backgrounds should be separated from halftone plates.
   Areas with heavy ink coverage may need to be printed twice to ensure even color density.
   Pay attention to gradient transitions — uneven tones or banding may occur if not adjusted properly.
4. Image adjustment considerations
   a. Consider the customer’s printing conditions — adjust tone curves accordingly. Typically, slightly reducing tone values helps compensate for dot gain.
   b. Adjust based on the characteristics of flexographic printing — for example, add dots in highlight areas to prevent dropouts, or control the tonal range of the black plate.
   c. Consider plate thickness and hardness — softer or thicker plates tend to expand more during printing, so highlight compensation may need to be slightly increased.
   d. Adjust according to screen ruling (line count) — higher line screens require more precise adjustments; lower line screens may need selective sharpening or tone modification depending on the artwork.
   e. Adapt to the customer’s product type — for example, printing for milk cartons, paper cups, or corrugated boxes each has unique material characteristics and requirements that should guide image adjustments.