Tone Value Increase

/toʊn ˈvæljuː ˈɪnkriːs/

General Definition

Tone Value Increase (TVI) / Dot Gain refers to the phenomenon where the physical size of the Halftone/Dot on the printed substrate becomes larger than the size of the halftones created on the plate during lithography. This physical expansion of the dot causes the color in that area to appear darker than the designer intended. TVI is the technical term and measurement for this phenomenon, which is a key print defect.

Real-World Usage

Dot Gain is the single most critical factor in color shift and the loss of Gray Balance in four-color printing. Quality Control personnel must understand this concept to implement the appropriate Compensation Curve during the prepress and RIP stages. Since Tone Value Increase (TVI) darkens the CMYK colors on the press, the Quality Control team must manage this color alteration by accurately setting the printer's output for every combination of paper (Coated or Uncoated) and ink.

Quality Control personnel need to maintain a standard TVI curve for every paper and press combination. Ignoring Dot Gain not only makes images look murky and dirty but also obliterates the distinction between two adjacent colors in the same tonal range (e.g., the difference between an 80% and a 90% halftone dot). If not precisely controlled, this defect leads to the loss of shadow detail and flattening of dark areas in the print job.

Consultant's Note

ur consultant's advice is to never use a fixed TVI curve across all projects. The amount of Dot Gain is significantly higher on uncoated papers than on coated stocks. For uncoated papers, the Production Manager must intelligently lighten the shadow areas during prepress so that the final color after dot expansion closely matches the original target.

Dot Gain is typically caused by the following factors during printing: 1. Inappropriate substrate material causing excessive ink absorption, 2. Excessive pressure from the printing cylinders, and 3. Unbalanced ink viscosity (thickness). Production Managers must continuously measure the color bars on the printed sheet using a Densitometer to ensure the press's TVI curve does not deviate from the ISO 12647 standard. Diagnosing these factors and reporting the issue to the operator is key to maintaining quality and preventing material waste.

Aligned with: ISO 12647 / G7 / Color Management Workflows