7 Replies Latest reply on Jul 30, 2009 10:50 AM by Jim_Babbage

    bug in fireworks CS4 when exporting 24/32bit png with transparent alpha?

    HdotNET

      Hi there,

       

      I recently upgraded to CS4 from CS3 and am quite disappointed to find that the png export facility for 24 or 32 bit png's is next to useless on my installation of Fireworks (Vista). I have a colleage who has reported the same behanviour on his mac.

       

      Please see this native fireworks CS4 png file and attempt to export it as 24 or 34 bit png, ensuring the canvas is transparent (it shuold be already)...

       

      http://www.capitalh.net/demo-bug.png

       

      Viewing in preview mode in CS3 would show the png with its alpha channel indicated by the chequered transparent pattern. Exporting it as such would produce the desired result > a png with a nice blended alpha channel.

       

      Viewing in preview mode in CS4 shows a horrible render of the image on a white background. Exporting the image produces the same result. Please see this link for confirmation:

       

      http://www.capitalh.net/demo-bug-export.png

       

      Please also see this simpler image, this time using a simple ellipse shape:

       

      http://www.capitalh.net/demo-bug-export-simpleshape.png

       

      You'll notice that it is not transparent, and the ellipse has not been anti-aliased.

       

      Can anyone shed some light on this behaviour?

       

      Exporting png's as such is something that I do daily at work, and is a basic requirement of an image editting application targetted at web design.

       

      Am I doing something wrong? I've been using Fireworks since 2003 so I'm inclined to think that I'm not.

        • 1. Re: bug in fireworks CS4 when exporting 24/32bit png with transparent alpha?
          HdotNET Level 1

          A bit of extra info, I'm running Fireworks CS4 version 10.0.3.011...just did the update via adobe updater.

          • 2. Re: bug in fireworks CS4 when exporting 24/32bit png with transparent alpha?
            Jim_Babbage Level 4

            Transparency is only available when the file is exported as PNG 8 or 

            PNG 32. The sample you have in uploaded was optimized for PNG 24. When 

            I switched the optimization to PNG 32, the file exported as expected.

             

            The simple shape PNG file appears to be a solid bitmap, not a vector 

            ellipse. In this case, switching the optimization setting to PNG 8 

            with Index Transparency solves the problem.

             

            HTH

             

             

            Jim Babbage

            • 3. Re: bug in fireworks CS4 when exporting 24/32bit png with transparent alpha?
              HdotNET Level 1

              Fancy that... you're right. Just tried it in CS3 and its the same.

               

              Strange, however, as from what I've read alpha transparency is supported in 24-bit mode...

               

              FYI, the sample shape png is an exported file at 24bit, not a native fireworks working file.

              • 4. Re: bug in fireworks CS4 when exporting 24/32bit png with transparent alpha?
                pixlor Level 4

                HdotNET wrote:

                 

                Strange, however, as from what I've read alpha transparency is supported in 24-bit mode...

                 

                 

                Well, what you read was either misleading or incorrect.

                 

                A 24-bit image means 8 bits for red, 8 for green, and 8 for blue (8+8+8=24). A bit is a BInary digiT; computers use base2 to count, not base10. Now, 8 bits of color means you can have as many colors as you can express with 8 digits in base2. With 8 bits, we can count to 28 which is 256. The phrase "24-bit image" simply means a standard image with 256 values each of red, green, and blue (256*256*256=16.7 million colors).

                 

                A 32-bit image has those same 8 bits for R, G, and B, plus 8 bits (256 values) of transparency.

                 

                 

                PNG8 is an indexed palette of 256 values of RGBT. You can have any combinations you want, you are just limited to 256 of them. Your index is 8 bits.

                • 5. Re: bug in fireworks CS4 when exporting 24/32bit png with transparent alpha?
                  HdotNET Level 1

                  That's a bit, um, oh never mind. Would've been a rubbish joke anyway.

                   

                  Back to my original confusion...

                   

                  If fireworks is unable to export a transparent png at 24bit, then why have the option?

                   

                  (granted the option is acutally implied, not given)

                   

                  Also, why the horrible rendering on preview and export?

                   

                  And also, why all this confusion related to Photoshop, seems Adobe really aren't helping the issue:

                   

                  http://forums.adobe.com/thread/152434

                  • 6. Re: bug in fireworks CS4 when exporting 24/32bit png with transparent alpha?
                    pixlor Level 4

                     

                    That's a bit, um, oh never mind. Would've been a rubbish joke anyway.

                     

                     

                    Aww...pooh. I love "rubbish" jokes!

                     

                     

                    If fireworks is unable to export a transparent png at 24bit, then why have the option?

                     

                    (granted the option is acutally implied, not given)

                     

                    Also, why the horrible rendering on preview and export?

                     

                    Transparency for 24-bit isn't an option and isn't implied. Create a FW document with a transparent canvas. Go to File>Image Preview. If you select PNG8 as your export option, then you have drop-downs for No Transparency, Index Transparency, or Alpha Transparency. PNG32 shows the checkerboard where the document is transparent. If you select PNG24, you do not have the transparency options. Transparent areas in your document are set to white, just as they are if you select the JPEG format. Try it.

                     

                    I don't know why your rendering is horrible. I'd have to see your image.

                     

                     

                    And also, why all this confusion related to Photoshop, seems Adobe really aren't helping the issue:

                     

                    http://forums.adobe.com/thread/152434

                     

                    Possibly Adobe thought it was less confusing, as they didn't have to go into the math. However, you do see Linda Rathgeber's answer, that the Photoshop convention is...well...misleading? (I'd call it wrong, but that's just me. ) It's just one other issue to bring into alignment as Adobe works to merge the Macromedia offerings into their line.

                    • 7. Re: bug in fireworks CS4 when exporting 24/32bit png with transparent alpha?
                      Jim_Babbage Level 4

                      You are in a Photoshop mindset. PS doesn't offer PNG 32 as an explicit 

                      option; it offers PNG 24 with an option for transparency (which, when 

                      selected gives you PNG 32.)

                       

                      Fireworks has always broken it out as PNG 8 (index and alpha 

                      transparency), PNG 24 (no transparency) and PNG 32 (automatic alpha 

                      transparency if the canvas is set to transparent. When Adobe took over 

                      Macromedia, I can only assume it wasn't a priority to unify these 

                      settings over both applications.

                       

                      As with Lorraine, I can't comment on the horrible rendering. Things 

                      seemed to work fine when I set the necessary export options.

                       

                      HTH

                       

                      Jim Babbage