In painting, transposing is similar to shifting a piece of music from a major key into a minor one. We hear choral groups do this all the time, beginning a song in a bright, burst of harmonious acclaim in a major key, then transitioning to a quieter, more pensive minor key restatement. We recognize the tune, even though is mode has moved to a more meditative expression. 

Sometimes our response to a scene or even a portrait might not call for boldness, rather we might feel more contemplative or wistful or reflective about it. One way we can echo this is to transpose the values by compressing their relationship, reducing their contrasts.

When we transpose, we change the form into a different mode whereas when we translate, we interpret what we're seeing as closely as we can to our perception of it. To translate, then, the values of our colors will range from the darkest dark we are seeing to the lightest lights. We can transpose by dropping those and interpreting our painting within a mid-value range.