More on FAQ #405

405. Why doesn’t TCQ spell out which specific “light”-related changes are allowed, the way allowable non-“light”-related changes are carefully spelled out?

(This is a reference to TCQ’s Allowable Changes; “light-related changes” are #10 on that list.)

The answer is, “Because there is no limit on the degree of light-related changes that are permissible in order to meet Q7.” (See “B” here)

For almost any common kind of “light”-related change, it is possible to picture a situation in which that change would be necessary for the photograph to meet Q7.

For example, there aren’t any “light”-related changes more radical than changing every color in a photograph to its opposite — and yet that is what has been needed to produce a trustworthy result from billions of photographs recorded onto a film negative.

(Converting “negative” images to “positive” is of course allowed by TCQ.)

When discussing allowable “light”-related changes in TCQ photographs, what matters is not the nature or degree of the change but whether the result meets Q7.

See the page on light if it is unclear why TCQ severely limits non-“light”-related changes.