OK, for a quick fix I rewrote it to output the image data to temporary files (in the full script there's an image for each of the CMY layers) and then write those out to stdout.

I couldn't work out from Image::Magick how to get the binary data out using GetPixels to match the binary data that I got from writing out the files, at some point I'll go and ask the ImageMagick list and that will let me do without the temporary files.

Thanks for your replies, this one was a puzzler to me, but I'm no perl guru! This is a snippet of what worked for me:

...

binmode STDOUT;
$yellow->Write('gray:/tmp/yellow');
open(FIN,"</tmp/yellow") || die("cannot access file /tmp/yellow\n");
while (sysread FIN, $buffer, 4096) {
  print $buffer;
}
close FIN;

print("\r");
...

[download]

In reply to Re^3: STDOUT buffering problem by illtud
in thread STDOUT buffering problem by illtud

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.