KWE International, Inc. Services. Experiment with Pantone Colors.

Experiment with Pantone Colors

The camera calibration experiment was conducted for consumer digital cameras Canon PowerShot G2, Canon PowerShot G5, Minolta DiMAGE 7, and Sony DSC F828.

Eight Pantone cards containing fifty-six colors were used. By illuminating Pantone cards with Illuminant D65, a set of reflected light sources was created. After correcting for the unevenness of the light distribution over the object and the unevenness of the matrix sensitivity, the source might be described by a set of sRGB numbers given on a Pantone Card for every color. Color Capturing Error was considered as the difference between data provided for the color by corresponding Pantone Card and the average data obtained as a result of RAW image data processing. To compute the RMSE, sRGB data was converted to Lab format, as it had been recommended by CIE (Commission Internationale de l'Eclairage).

For easier comparison of the results of the experiment, sRGB digital data was transformed into graphical form, where the original color, Camera Maker's color, and KWEII's color were placed side by side.

Each cell in the tables, which are referred by the following links:
Canon PowerShot G2, Canon PowerShot G5, Minolta DiMAGE 7, and Sony DSC F828,
has been divided into three parts:

An Original color was placed in the left half of each color-square;

A color received after Camera Maker's processing was placed in the right top corner;

A color received after KWEII’s processing was placed in the right bottom corner.

The method used has several limitations:

Pantone sRGB tables include less than a half of all colors visible by a human.

Pantone tables have hundreds of colors, however only 56 colors are selected for the experiment.

Lights from different spectral characteristics can cause the same color sensation. Paint, used in the Pantone Tables, is only one of many possible realizations of a color.

Even though this method has limitations, the obtained results can be useful for quantitative assessment of digital image processing improvement.

If this experiment with Pantone is conducted not with D65, but with a narrow band source (an artificial color), or if the color base is enlarged beyond the bonds of sRGB, the error could be much bigger. In order for KWEII specialists to lower error for all colors, including artificial colors and colors beyond sRGB range, and reach the theoretically best solution for each particular set of optics, filters and sensors, the spectral characteristics of the particular system are necessary.

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