| 摘要 |
Paper is provided with resistance to photocopying or tran smission by telefacsimile by spatial spectral modulation of the paper reflectance at a specific single or preferably multiple frequencies. Such paper has a coloured pattern of at least two colours repeating in at least one dimension of a face of a paper with at least one frequency in the range of from about 0.5 to about 50 times per cm. The colours contrast with black or similar dark colour to permit black or similar dark coloured information to be visibly readable when applied to the coloured pattern. The colours also cooperate with such information to provide a document resistant to photocopying and transmission by telefacsimile. |
