Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Daniel Staver" 
<daniel@p...> wrote:
> Does there exist an uncompressed version of Paul Roark's 21step wedge?
> The one in the file section is JPEG compressed and very uneven along the
> gradient, showing distinct vertical lines. It's hard to see on screen,
> but it really shows up in the prints. The same thing is present in the
> technical.psd file that is floating around (at least some versions of
> it).
> 
> --
> Daniel Staver
> http://daniel.staver.no

Hi Daniel,

The compression probably messes up some of the transitions but I think
the main thing you are seeing with the vertical lines is just the individual
256 steps of gray.  Photoshop will create two kinds of gradients -- 256
hard edged steps and smooth dithered gradients.  The "dither" option
in the Gradient tool there a check box for the two kinds.

It's real easy to fix up the 21step.  Just select the top half and make a new
gradient with dither on.  Select the bottom half, make a gradient with
the dither off, and posterize to 21 levels.

Roy