5 Replies Latest reply on Feb 6, 2012 7:50 AM by browntimmy

    Horizontal Pixel Banding in Exported .PNG files

    Davizual Level 1

      Hello I have this Horizontal Pixel Banding issue when exporting 24-bit transparent PNG files.

      I am using Illustrator CS5 (15.0.0) on a Win 7 64-bit machine.

       

      Steps to reproduce bug:

      1. Create an object like a circle with a gradient fill, put transparent objects over top. Add FX to the front objects like feathering, and "mesh tool" gradients.

      2. Export as a .PNG at 400 dpi, transparent with supersampling anti-aliasing on.

      3. View the created image file.

       

      Results: PNG Image contains unwanted 1 pixel-high horizontal lines spaced uniformly by 10 pixels in varous places on the circle object.

      Expected results: PNG file should be smooth and contain no banding/ horizontal lines.

       

      I load the same file into CS4, perform the same operation, and the resulting .PNG file renders as expected, with no banding.

       

      Take a look at the results below.  (Note: this is a cropped area of the original file.)

      Banding Test CS5 sm.png

      The above example is how it looks in CS5. Note the 1 pixel-high horizontal banding spaced every 10 pixels.

       

      Banding Test CS4 sm.png

      The above example is how it looks in CS4.  No banding

       

      Can someone tell me what might be wrong, or is this a bug in CS5 (15.0.0)?

       

      Thanks, Dave

        • 1. Re: Horizontal Pixel Banding in Exported .PNG files
          Mylenium Most Valuable Participant

          Banding is the wrong term. These are genuine disturbances in the file structure, i.e. missing pixel data. Looks like something going on with interlaced options for PNGs. have you tried otehr PNG modes? In which app are you viewing the result?

           

          Mylenium

          • 2. Re: Horizontal Pixel Banding in Exported .PNG files
            Jean-Claude Tremblay User Group Manager

            Hi Dave, I think you have experimenting one of the bug in the shipping CS5. You are not alone having such missing pixel stripes. I have been dealing with that recently too. This is happening each time to ask illustrator to render a gradient mesh. This is happening for JPG, PSD or PNG format with the Export command, or the Rasterize command & Effect and I have also seen it when opening/rasterizing the file in photoshop directly or via smart object. Pretty nasty bug! The only reliable workaround is to save it down to CS4.

            1 person found this helpful
            • 3. Re: Horizontal Pixel Banding in Exported .PNG files
              Davizual Level 1

              Jean-Claude,

               

              Thanks so much for taking the time to explain what was going wrong!  Although it is not a fix, it helps me understand that it is not on my end and I will continue to let Adobe know about it so they can fix it soon.  I am surprised it was not patched sooner.  I am glad that I left CS4 on my machine, so I will continue to process my images by saving the file as a legacy CS4 image, opening CS4 and exporting from there. 

               

              I also tried to play with the rasterizing but it yeilded no fix, it just put the lines in different places...

               

              Again, thanks for your help!

               

              Dave.

              • 4. Re: Horizontal Pixel Banding in Exported .PNG files
                Davizual Level 1

                Great News!

                 

                Adobe updated Illustrator to fix this problem.

                you can download it from http://www.adobe.com/downloads/updates/

                look for:

                Adobe® Illustrator® 15.0.1 CS5 Update — all languages

                August 6, 2010

                 

                The Adobe® Illustrator® 15.0.1 update addresses a number of issues related to stability, including the following:

                • Out of memory problems specific to Macs with RAM exceeding 4gb, including failure of shortcut keys, rulers, or file open have been addressed.
                • Glyph Panel issues have been addressed.
                • Several crashes occurring at launch or quit have been addressed.
                • A crash when traversing a variable data set containing linked images has been addressed.
                • An issue with white lines appearing on rasterized gradient mesh objects has been addressed.

                 

                 

                 

                I tested it and thank goodnes it's fixed.  Now I can use CS5 again...

                • 5. Re: Horizontal Pixel Banding in Exported .PNG files
                  browntimmy Level 1

                  Is it just me or has this problem crept back in to Illustrator 15.1? When I rasterize certain psd images I get those same lines of missing pixels.