What is "density correction?"

[crossboard]

I was recently asked, "What is 'density correction?' ." I honestly could not come up with a good answer. Does this have to do with: tonal contrast? levels? color correction? film grain? something else?

Is this a terminology that goes back to processing real film stock, but has become more archaic in the digital world? How many times do you talk about "density" in a photograph?

[KR1156]

it's like measuring "weight" of an image by tonal values.

let's say you have a model with one leg with nice exposure, nice shadows and highlights good shape and whatnot....and the other is a little flat and bright, maybe being hit by too much light, and someone will say "match that leg's density to the other leg" basically it means to add more tone to it and match the "weight" or density of the other leg.

[dippy]

It may also refer to ink density as it pertains to four-color printing. For example, black can be made up of 100% black ink and 0% cyan, magenta and yellow. But that's less "dense" than a black made up of 100% of black, cyan, magenta and yellow inks.

I've had to boost (or "correct") the density of some images because the blacks were not rich or saturated enough, by boosting the C, M and Y channels.

[TommyO]

It may help us to know in what context the term came up. Was it during a discussion of inks, photography, filters, ... ? Density has different meanings in each field.