imread.m fails reading/writing 16bit images correctly

[Tatsuro MATSUOKA]

Hello

I have tested in my cygwin build using octave-3.2.1-rc1 on cygwin-1.5.25-15.
Graphicsmagick is configured with 
CC=gcc-4 CXX=g++-4 F77=gfortran-4 CFLAGS='-O3 -fomit-frame-pointer' CXXFLAGS='-O3
-fomit-frame-pointer' FFLAGS='-O3 -fomit-frame-pointer'  ./configure --enable-shared  --enable-static
--disable-openmp --with-quantum-depth=16 --without-threads --with-windows-font-dir=C:/WINDOWS/Fonts


octave:4>  imwrite(uint16(12345),"test.tiff");
octave:5> img=imread("test.tiff")
img = 48
octave:6> class(img)
ans = uint8
octave:7> imfinfo("test.tiff")
ans =
{
  Filename = /cygdrive/d/usr/Tatsu/program/Octave/test2/test.tiff
  FileSize =  261
  Height =  1
  Width =  1
  BitDepth =  16
  Format = TIFF
  LongFormat = Tagged Image File Format
  XResolution = 0
  YResolution = 0
  TotalColors =  1
  TileName = 
  AnimationDelay = 0
  AnimationIterations = 0
  ByteOrder = undefined
  Gamma = 0
  Matte = 0
  ModulusDepth =  13
  Quality =  75
  QuantizeColors =  256
  ResolutionUnits = undefined
  ColorType = grayscale
  View = 
  FileModDate =  2-Jul-2009 08:33:32
}

The behaviors are the same as your reports.
I will check your changeset from now.


Regards

Tatsuro

--- Benjamin Lindner  wrote:

> Hello,
> 
> using current development sources on mingw32, together with 
> graphicsmagick-1.3.5 configured with --quantum-depth=16, imread does not
> correctly read 16bit images.
> 
> octave.exe:2:C:\> imwrite(uint16(12345),"test.tiff");
> octave.exe:3:C:\> img=imread("test.tiff")
> img = 48
> octave.exe:4:C:\> class(img)
> ans = uint8
> octave.exe:5:C:\> imfinfo("test.tiff")
> ans =
> {
>   Filename = C:\test.tiff
>   FileSize =  261
>   Height =  1
>   Width =  1
>   BitDepth =  16
>   Format = TIFF
>   LongFormat = Tagged Image File Format
>   XResolution = 0
>   YResolution = 0
>   TotalColors =  1
>   TileName =
>   AnimationDelay = 0
>   AnimationIterations = 0
>   ByteOrder = undefined
>   Gamma = 0
>   Matte = 0
>   ModulusDepth =  13
>   Quality =  75
>   QuantizeColors =  256
>   ResolutionUnits = undefined
>   ColorType = grayscale
>   View =
>   FileModDate = 29-Jun-2009 11:40:51
> }
> 
> The reason (I believe) is that __magick_read__.cc (staring at line 418) 
> determines from ModulusDepth the number of bits required to store image data 
> into incorrectly.
> With the above Modulusdepth=13, the calculated bitdepth is 8, when it should 
> be 16.
> 
> The attached changeset fixes this, but it still does not work correctly.
> 
> octave.exe:5:C:\> imwrite(uint16([12345,12346,12347]), "test2.tiff");
> octave.exe:6:C:\> img=imread("test2.tiff")
> img =
> 
>   12344  12345  12346
> 
> the values read are off-by-1.
> 
> And apparently they are already written off-by-1
> 
> c:\> tiffinfo -d test2.tiff
> TIFF Directory at offset 0xe (14)
>   Image Width: 3 Image Length: 1
>   Bits/Sample: 16
>   Sample Format: unsigned integer
>   Compression Scheme: None
>   Photometric Interpretation: min-is-black
>   Samples/Pixel: 1
>   Rows/Strip: 1365
>   Planar Configuration: single image plane
>   Page Number: 0-1
>   DocumentName: test2.tiff
>   Software: GraphicsMagick 1.3.5 2009-01-26 Q16 http://www.GraphicsMagick.org/
> Strip 0:
>  38 30 39 30 3a 30
> 
> and 0x3038 equals 12344 decimal, so something's wrong at creating the image file
> I couldn't yet figure out why this is so.
> Can someone confirm this behavoiur? 
> 
> benjamin
> -- 
> GRATIS f将舐 alle GMX-Mitglieder: Die maxdome Movie-FLAT!
> Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01
> > # HG changeset patch
> # User Benjamin Lindner <lindnerb at users.sourceforge.net>
> # Date 1246274961 -7200
> # Node ID c39f66e65f188f1f405f6ed74bb8c3b757e2a203
> # Parent  34c8e1d9c9c273e10ad7f6cc9fdd8ddd5db6ed77
> determine correct image bitwidth in __magick_read__.cc
> 
> diff -r 34c8e1d9c9c2 -r c39f66e65f18 src/ChangeLog
> --- a/src/ChangeLog	Thu Jun 25 09:44:06 2009 +0200
> +++ b/src/ChangeLog	Mon Jun 29 13:29:21 2009 +0200
> @@ -1,3 +1,8 @@
> +2009-06-29  Benjamin Lindner <lindnerb at users.sourceforge.net>
> +
> +	* DLD-FUNCTIONS/__magick_read__.cc (F__magick_read__): Determine correct number 
> +	of bits required when reading images.
> +
>  2009-06-14  Jaroslav Hajek  <highegg at gmail.com>
>  
>  	* DLD-FUNCTIONS/lookup.cc (Flookup): Support character array lookup.
> diff -r 34c8e1d9c9c2 -r c39f66e65f18 src/DLD-FUNCTIONS/__magick_read__.cc
> --- a/src/DLD-FUNCTIONS/__magick_read__.cc	Thu Jun 25 09:44:06 2009 +0200
> +++ b/src/DLD-FUNCTIONS/__magick_read__.cc	Mon Jun 29 13:29:21 2009 +0200
> @@ -416,11 +416,15 @@
>    else
>      {
>        unsigned int depth = imvec[0].modulusDepth ();
> -      int i = 0;
> -      while (depth >>= 1)
> -        i++;
> -      depth = 1 << i;
> -
> +      if (depth > 1)
> +	{
> +	  --depth;
> +	  int i = 1;
> +	  while (depth >>= 1)
> +	  i++;
> +	  depth = 1 << i;
> +	}
> +      
>        switch (depth)
>          {
>          case 1:
> > _______________________________________________
> Bug-octave mailing list
> Bug-octave at octave.org
> https://www-old.cae.wisc.edu/mailman/listinfo/bug-octave
> 


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