Sham positive

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

As apparent positive is referred to in the photograph is a scarce or underexposed negative , the result of the dark field principle as against a dark background Positive appear.

Sham positives are used in various direct positive photographic processes such as ferrotype ( tin [y] type ), ambrotype ( melanotype ) and pannotype .