Geograph - photograph every grid square

This Is Not A Photography Site
Highlighting that geograph is not primarily about 'artistic' photography, preferring to concentrate on documenting the land, warts and all. Sometimes that means excellent photography, sometimes not - but first and foremost we welcome contributions from photographers whatever the skill level.

[the beginnings of an answer]

Put simply, photographs are made of light. In good light, today's digital cameras make it difficult to take a technically poor photo. Sometimes, though, photos unavoidably come out dark or grey because the subject was in shadow, or it was getting late; worst of all, a cloud appeared overhead and followed you round while the distant landscape was bathed in sunshine. There are ways of making these photos reveal their subjects better.

This isn't a highly technical answer. It refers to features of commonly-used image editing or image enhancement software.

[to be continued]