1 Reply Latest reply on Aug 9, 2006 8:03 AM by Newsgroup_User

    Paint Shop Pro Moiré Pattern Removal = ?

      I feel that I should change over completely to Fireworks 8 and the best way to do this would probably be to remove my beloved Paint Shop Pro from my computer! The one major thing that I have been unable to find in Fireworks (Dreamweaver) 8 is how to remove Moiré Patterns. I find it invaluable to remove these patterns from newspaper photographs and would be loath to loose this facility. Paint Shop Pro gives the following instructions and description

      Use the Moiré Pattern Removal dialog box
      to remove undesirable patterns produced in a scanned image as well as patterns from photographs printed on textured paper.

      Ø Notes: You can apply this effect to greyscale and 24-bit colour images. If necessary, increase the colour depth of your image to make the command available.
      To apply the effect to a selection, create the selection before choosing the effect.

      Jasc Software, Inc.

      Can anyone make a suggestion?
        • 1. Re: Paint Shop Pro Moir? Pattern Removal = ?
          Level 7
          On Wed, 09 Aug 2006 00:11:57 +0400, shampayne
          <webforumsuser@macromedia.com> wrote:

          > The one major thing that I have been unable to find in Fireworks
          > (Dreamweaver)
          > 8 is how to remove Moir? Patterns.

          Well, from your post I decide that you are using Windows. Then, I may
          suggest you some third-party freeware, that, although not being as much
          user friendly as PSP and FW, often is much more efficient when it comes to
          removing moire or halftone screen patterns. The software is called "Image
          Analyzer" and is available for free here:


          The key feature you need is called "Frequency domain filter".

          Now a bit of theory on Fourier transform and frequency spectrum stuff
          (just in case you weren't learning related math at University).

          FT is about representing the image (or other data) as a composition of
          sine functions (sine function is periodic or "harmonic" wave). From
          ordinary average guy's point of view, describing the photo as huge set of
          waves added together is senseless, but scientists think different.
          Interesting thing happen, if our image *really* have some periodic
          component in it. Regardless of what is this component - periodic texture
          of the wall, or ladder, or just periodic pattern of printed halftone in
          image, or result of interaction of periodic halftone with periodic nature
          of scanning which we know as "moire" - it will give us high peak in
          frequency spectrum (that is, in image representing how intensive are waves
          of dirrerent frequencies). We can detect that peak and, if necessary, edit
          or even remove it, thus editing or removing this particular signal from
          the image.

          Now we go to the practical part. You should scan your images at ppi at
          least twice as high as printing halftone screen lpi. Most printings are
          done with lpi about 150, and newspapers often at even lower values, so you
          should scan them at 300 ppi at least (and without any software sharpening
          scanner may offer you). Then open image with Image Analyzer. Then go to
          Filter -> Frequency domain filter. Now you see the frequency spectrum of
          the image. In the dialog, you may need to click "View scale" down scale a
          couple of times so the image is easier to view. The image you see is
          likely to look like the galaxy of white stars spreading from the top
          center part to the edges. The top center part is brightest. Beside it, you
          are likely to see some additional bright stars (high peaks) apart from it,
          forming some sort of a pattern. These are the peaks representing our
          "parasite" periodic pattern in the image. So you should just paint black
          over them, checking out the intermediate result with "Preview" button.
          Important point is: don't hit the bright spot at the top center area, this
          is useful signal. Only hit the "lone stars" far from it. Once you're
          satisfied, hit "Ok" and save the image.

          Althought the technique may look complicated (again, only in case you
          weren't learning related math at University), I often found it to be most
          efficient when dealing with halftone or moire. I can make some suggestions
          more related to "pure FW" way of doing job if you're interested, but I
          personally highly recommend learning this trick.

          Ilya Razmanov
          http://photoshop.msk.ru - Photoshop plug-in filters