exportimage png with alpha transparency


    Mar 04 2006 | 11:33 pm
    hi
    i am trying to export a sequence of pngs
    from a webcam after doing a background subtract
    exportimage works fine if go direct from cam into matrix
    but the resulting png if i pass thru a jit.op @op- is grey
    is this a limitation? or am i doing somethin wrong?
    simple sample patch below
    thanks in advance
    jhave
    //
    max v2;

    • Mar 07 2006 | 4:54 am
      Hello,
      re:recording alpha-transparency pngs using exportimage after a jit.op @op-
      i'd sincerely appreciate it if someone from Cycling could let me know if this is a limitation of Jitter
      or if its just the machine I am using (its a university box
      running MaxMSP 4.3.2
      I am facing a mild deadline and have reached the end of explorable options.
      Thanks
      David
    • Mar 07 2006 | 5:12 am
      I'm not from Cycling, but I just tried your patch png export seemed
      to work fine for me on both the original image and a jit.op -
      modified image. I am running OS X 10.4.5 max 4.5.6 and jitter 1.5.2.
      Cheers,
      Christopher
    • Mar 07 2006 | 5:20 am
      many thanks
      very very helpful to know
      (the pngs after op for me are just grey)
      question now is: is this 4.3.2 limitation?
      or a bad codec on this particular machine?
      thanks again, i'd been banging my head against the wall
      thought i was doing something wrong...
    • Mar 07 2006 | 9:26 am
      This certainly has nothing to do with your version of Max, but might
      have something to do with your version of Jitter, which you haven't
      mentioned. It might also simply be a difference between the QuickTime
      version you are using (also not mentioned) and QuickTime 7, which
      Christopher Baker is using. It's also not clear what OS you're using, or
      what platform you are on. All of these factors could contribute to the
      problem.
      You may find the BUG REPORTING GUIDELINES (copied below) helpful in
      formulating reports like this, since vague reports tend to fly under our
      radar.
      jb
      BUG REPORTING GUIDELINES
      Please report any problems you experience with clear and complete
      information, including steps to reproduce, software and system
      information, and where possible, an isolated example patch and crash
      log. Something like the following would be ideal. This makes it
      easier for us to find and fix the problems you experience. Without
      such clear and complete information, it is less likely we will be
      able to.
      Summary:
      Provide a descriptive summary of the issue.
      Steps to Reproduce:
      In numbered format, detail the exact steps taken to produce the bug.
      Expected Results:
      Describe what you expected to happen when you executed the steps above.
      Actual Results:
      Please explain what actually occurred when steps above are executed.
      Regression:
      Describe circumstances where the problem occurs or does not occur,
      such as software versions and/or hardware configurations.
      Notes:
      Provide additional information, such as references to related
      problems, workarounds and relevant attachments.
    • Mar 07 2006 | 9:47 am
      jeremy,
      sorry if i deviated from the guidelines
      (i did provide a patch, and tried to be clear)
      and yes have now done a test on another machine
      using same patch as posted before
      (previous unsuccessful export
      machine was
      mac os 10.3, max 4.3.2, jitter 1.2.2.
      successful test machine:
      windows xp, max 4.3.2, jitter 1.2.2)
      So the png does export:
      BUT without transparency (subtracted regions are simply black).
      is there a methodology for exporting a movie or sequence of images with transparency ?
      (i have investigated cv.jit and jitter help files and searched archives without any clear answers)
      jhave
    • Mar 07 2006 | 9:58 am
      Looks like the difference is either platform or QuickTime version then.
      If the QuickTime versions are identical on the 2 machines, then it's
      probably a Jitter issue (although we are no longer making updates to the
      Jitter 1.2.x code base). If not, you need to bring them into sync to
      test this out. I am 95% sure that this is going to turn out to be a
      QuickTime issue.
      jb
    • Mar 07 2006 | 10:06 am
      thanks for yr persistence Jeremy,
      I will investigate Quicktime versions on both machines tomorrow and let you know how it works out.
      In the meantime, my central more functional question remains:
      is it possible export a png with transparency (in photoshop save-for-web this option is referred to as png-24 : Perhaps this codec is not possible to export with Jitter? )
      Basically, I am seeking a way to export movies with transparency and assumed png sequences were the answer. I'd really appreciate it if anyone could let me know if this is a feasible path from a technnical standpoint.
      Thanks again,
      jhave
    • Mar 07 2006 | 5:46 pm
      On Mar 7, 2006, at 2:06 AM, david jhave johnston wrote:
      >
      > In the meantime, my central more functional question remains:
      > is it possible export a png with transparency (in photoshop save-
      > for-web this option is referred to as png-24 : Perhaps this codec
      > is not possible to export with Jitter? )
      This should be possible provided it has been appropriately selected
      in the export image dialog (millions of colors +, should be 32 bit
      with alpha)
      > Basically, I am seeking a way to export movies with transparency
      > and assumed png sequences were the answer. I'd really appreciate it
      > if anyone could let me know if this is a feasible path from a
      > technnical standpoint.
      This can also be accomplished with jit.qt.record and any codec that
      supports an alpha channel such as animation or the several codecs
      discussed at the following site.
      -Joshua
    • Mar 27 2006 | 3:05 am
      joshua,
      very sorry to bother u again about something that must be quite simple...
      but i have done a test exporting a chromakeyed movie from jit.qt.record using the "animation" codec,
      and the alpha channel is black
      is there a flag that needs to be set to enable alpha channel tranparency?
      patch setup:
      jit.qt.chromakey --> jit.qt.record
      "write TEST.mov 15. animation max 600"
      many thanks
      david
    • Mar 27 2006 | 4:14 am
      CORRECTION: animation codec does have an alpha channel....
      it just wasn't readable by sorenson.....
      thanks!