I downloaded the latest OpenJpeg v2 source.  I am writing JP2 images with
greater than 3 bands.  In jp2.c line 1427 the meth is set to 2 for bands
greater than 3.  This requires an ICC profiles to be written.  The library
just sets it to NULL in line 722.  If I write JP2 this way, other JP2
readers get upset.  The ECW SDK reader errors and crashes and Photoshop
display a ICC profile error but does recover and open the file.  I took a
quick look at the ICC profile specs and I didn't see anything about higher
bands covered. My current solution is to just change jp2.c to set the meth
to 1 and the color space to RGBs for bands greater than 3.  When I write
this way the ECW SDK opens it fine and so does Photoshop.  Is there any
problem with this solution?

winfried

----- Original Nachricht ----
Von:     Will K <willkem...@gmail.com>
An:      openjpeg@googlegroups.com
Datum:   15.11.2012 16:25
Betreff: [OpenJPEG] Writing JP2 openjpegv2, Colour specification box, ICC
 profile issue with greater than 3 bands

Sorry I gave the wrong line number.  The line is 2161.  It code looks like
this:

 if ((image->numcomps == 1 || image->numcomps == 3) && (jp2->bpc != 255)) {
  jp2->meth = 1; /* METH: Enumerated colourspace */
 } else {
  jp2->meth = 2; /* METH: Restricted ICC profile */
 }
 if (jp2->meth == 1) {
  if (image->color_space == 1)
   jp2->enumcs = 16; /* sRGB as defined by IEC 61966–2–1 */
  else if (image->color_space == 2)
   jp2->enumcs = 17; /* greyscale */
  else if (image->color_space == 3)
   jp2->enumcs = 18; /* YUV */
 } else {
  jp2->enumcs = 0;  /* PROFILE (??) */
 }

 Anyway, when numComps is greater than 3 jp2->meth gets set to 2.  Later in
the code the Meth 2 should write an ICC Profile, but it writes out a 0
instead.  I think it is best to not set meth 2 unless a real ICC profile is
going to actually be written.  I don't now the actual requirement about 4
band imagery, but the ECW and Photoshop JP2 readers do not seem to care if
the ICC profile is there.