Curves

Clive R. Haynes FRPS

Let's make other, very straightforward, alterations to the shape of the 'Curve' and the logic will become more apparent.

What happens if, instead of altering bending the shape of the curve we move it along the edges of the gradients?
Let's explore these options.

Above: Let's examine what's happening in the dialogue box above.
The pale red line indicates the starting point for the curve - we can refer to this as the 'normal position'. Any distortion or movement from 'normal' will affect the image in some way. It's a good idea to always bear in mind the slope of the line from corner to corner when beginning to make changes, as alterations to the shape of the curve can then be related to the starting point. In other word we can picture just how far from the straight line we have strayed.
Some people place a pen on the monitor screen from corner to corner of the 'Curves' dialogue box to see just how far from the straight line they have come.

In the example above we can see that the light grey area on the lower gradient scale, representing ('Input') 'light', has been pushed over to the left along the top edge. This instructs the ('Output') 'ink' to print everything to the right of the chosen grey area as white. Light greys become white.
This 'movement' has the additional effect of taking the whole straight line of the 'Curve' towards the left and this also lightens the image. The dark greys remain little affected and the black point remains anchored at the corner, black = black ink.