I need to find a pointer increment that when used repeatedly, describes a line of pixels running through an image at any angle.

To start with all I have is the starting and ending points of the line as (u,v) texture coordinates...

Look at the image and you see that the start and end points are (1, 0.21) and (0, 0.55) respectively.

I need a floating point increment value in order for the pointer to move along this line.

The pointer will be used on the raw data of the image that is held in an int array, the pixel data is stored as 32bit ARGB in that array.

This is really hard to explain. Sorry.

How do I calculate the increment for my pointer?