Characteristic curves of colour films

Negative curves

Reversal curves

To prepare a characteristic curve or curves for colour films it is necessary to measure the densities of each exposure step to red, green and blue light separately. One can then plot on the same graph three curves, one for each layer of the film.

A characteristic curve of a colour positive film.

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Negative curves

In a colour negative film the three curves are separated vertically since the orange integral mask in the film, the overall orange coloured base, has highest density to blue light, lowest density to red light. Colour print films are of much higher contrast [like black and white print films] but are characterised by three curves with a very low D.Min.

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Reversal curves

In a colour reversal film there is no integral mask, therefore, the three curves are almost coincident.