Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Jeff Randall" 
<jrandall@...> wrote:
>
> 
> Graham:  How did you create the circular gradient (not the circular 
> step-wedge)--maybe it's the maths?
>
Hi Jeff.
It did occur to me that maybe there was a problem in the initial 
construction of the circular targets, but i don't know enough about 
how Photoshop creates gradients to be able to comment.

In the hope that there's someone out there who does, here's what i 
did . . .

1) Added a few Guides to mark the centre and perimeter of my circle.
2) Used these to make a circular selection of the size i wanted.
3) Selected the Gradient tool with the Radial Gradient option.
4) Dragged from the centre of the circle to the perimeter.

This produced the lighter of the two targets. To produce the darker 
one (black perimeter) i simply used Invert before deselecting the 
circle. Stunningly simple really, but maybe there IS something 
happening in the maths (as you say) that means these gradients are 
less than perfect. They seem to be fine on screen.

To produce the stepped targets, i again used the simplest method i 
could think of - basically all i did was to posterize the gradient 
before deselecting. (Hence the unequal steps, which i mentioned in my 
original post.)

For the sake of completeness, i should maybe add that i used exactly 
the same technique to produce the linear ramp and step-wedges below 
the circular targets. The only difference was (obviously) that i used 
a rectangular selection and the Linear Gradient tool.

So, does anyone out there know why this technique might cause the 
banding people have reported? And (referring back to my post earlier 
today) can anyone see similar (though less distinct) banding in the 
linear ramp on their prints?

Regards.

graham