This International Standard specifies the procedure to be used for determining the whiteness of papers andboards. The values obtained correspond to the visual appearance of white papers and boards with or withoutfluorescent whitening agents when they are viewed under the CIED65 daylight illuminant. It is based onreflectance data obtained over the full visible spectral range (VIS) in contrast to the measurement of ISObrightness which is limited to the blue region of VIS.In addition, it specifies a method for adjustment of the UV-content to correspond to the D65 daylightilluminant[8][9], insofar as results obtained when fluorescent whitening agents are present are dependent uponthe UV-content of the radiation falling upon the sample. It is specific for the measurement of fluorescence in theblue region of the spectrum.This method is not applicable to coloured papers containing fluorescent dyes.This International Standard should be read in conjunction with ISO2469.NOTEA related standard, ISO11476[4], specifying the procedure for obtaining values corresponding to the appearance ofthese products under indoor illumination, has also been published.