M1 Measurement

/ɛm wʌn ˈmɛʒərmənt/

General Definition

M1 Measurement, defined by the ISO 13655 standard, specifies a color measurement method using a spectrophotometer where the ultraviolet (UV) light component is included and regulated to closely match standard daylight conditions (D50). The primary purpose of the M1 mode is to ensure that the effect of Fluorescence, caused by the presence of Optical Brightening Agents (OBAs) in the printing substrate, is accurately captured and factored into the resulting L∗a∗b∗ values. This mode is explicitly defined for clear differentiation from modes like M2 Measurement (which excludes UV light) and is part of the overall Color Measurement Classes collectively known as the M factor.

Real-World Usage

M1 Measurement has become the industry-standard method for measuring materials containing OBAs, such as many common coated and uncoated paper stocks. Unlike modes such as M0 Measurement and M2, M1 provides a more accurate prediction of the color appearance of the printed product under standard viewing conditions. Consistent M1 data is critical for color communication and for ensuring that the appearance of spot colors and process inks (CMYK) matches the intended visual reference.

Integrating M1 Measurement into the print workflow is crucial for accurate profile generation and validation, especially when aiming for standards aligned with FTA and Idealliance methodologies. By capturing the total color, including fluorescence, M1 ensures that color management calculations, profile adjustments, and press controls are reliable across different paper batches or different printing sites.

Consultant's Note

As a Color Management Specialist, the transition to M1 Measurement is a fundamental requirement for reliable color management systems that adhere to modern ISO standards. Relying solely on M0 or M2 data when printing on OBA-containing stocks leads to measurement inaccuracies, color discrepancies between print and proof, and unreliable densitometric readings. All modern spectrophotometers must be M1 compliant to ensure data integrity.

M1 is essential for calculating accurate Total Ink Coverage (TIC) limits, as fluorescent whitening can affect the visual appearance of deep shadows and solid areas. By measuring the full chromatic impact, M1 helps production managers avoid unnecessary adjustments and ensures that the color data used for quality control accurately reflects what the human eye perceives under a calibrated viewing environment.

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