I already posted a tutorial about alpha-curves that are good for shaping the alpha-channel. In this tutorial its all about Value or Chrome-Curves.
The channel of the curves-tool is set to the default of 'Value' (instead of Alpha).
Chrome-Curves are a way of shaping a gradient (for example), into something that looks metallic or chromed.
For demonstration purposes i filled a text selection (almanaque 145px) with a gradient:
(40ies) Grey to White (#666666 - #ffffff)
Chrome-Curves can have all sorts of shapes, from simple to extreme.
Basically its a wavy shape that goes up and down along the diagonal line in your curves diagram or, in the more extreme cases, from bottom to the top of the curves-tool dialog-box.
Here are some examples:
Curves applied to the gradient filled text:
For the next demonstration im adding a bevel to our text and then apply custom chrome-curves.
See how tweaking the curve, step by step, changes the chrome look:
More examples for chrome-curves shaped gradients:
Chrome-Curves on a bumpmapped layer:
Finally a different approach: bumpmapping a 50ies grey layer with a 6px blurred channel and then chrome-curves.