"miscellaneous update"

git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@567 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 40 insertions, 0 deletions

diff --git a/tifftopnm.html b/tifftopnm.html
index c14fe12c..e07387f0 100644
--- a/tifftopnm.html
+++ b/tifftopnm.html
@@ -20,6 +20,7 @@ tifftopnm - convert a TIFF file into a PNM image
 <br>
 [<B>-respectfillorder</B>]
 [<B>-byrow</B>]
+[<B>-orientraw</B>]
 [<I>tiff-filename</I>]
 
 
@@ -154,6 +155,9 @@ faster.  And because Netpbm code does more of the work, it's possible
 that it can be more flexible or at least give better diagnostic
 information if there's something wrong with the TIFF.
 
+<p>The Netpbm native code may do something correctly that the TIFF
+library does incorrectly, or vice versa.
+
 <P>In Netpbm, we stress function over performance, so by default we
 try Whole Image first, and if we can't get enough memory for the
 decoded image or TIFFRGBAImageGet() fails, we fall back to Row By Row.
@@ -169,10 +173,46 @@ your results.
 <b>tifftopnm</b> then scales them back to maxval 65535, but the lower
 8 bits of information is gone.
 
+<p>In many versions of the TIFF library, TIFFRGBAImageGet() does not
+correctly interpret TIFF files in which the raster orientation is
+column-major (i.e. a row of the raster is a column of the image).
+With such a TIFF library and file, you must use <b>-byrow</b> to get
+correct output.
+
 <P>Before Netpbm 10.11 (October 2002), <B>tifftopnm</b> always did Row
 By Row.  Netpbm 10.12 always tried Whole Image first.  <b>-byrow</b>
 came in with Netpbm 10.13 (January 2003).
 
+<dt><b>-orientraw</b>
+
+<dd>A TIFF stream contains raster data which can be arranged in the
+stream various ways.  Most commonly, it is arranged by rows, with the
+top row first, and the pixels left to right within each row, but many
+other orientations are possible.
+
+<p>This option says to produce an output image that represents the raw
+raster in the TIFF stream rather than the image the TIFF stream is
+supposed to represent.  In the output, the top left corner corresponds
+to the start of the TIFF raster, the next pixel to the right is the
+next pixel in the TIFF raster, etc.
+
+<p>This orientation is the same as the Netpbm formats use for their
+rasters, so it is easy for <b>tifftopnm</b> to do the conversion
+with <b>-orientraw</b>.  On the other hand, if the TIFF raster is not
+in that orientation and you don't use <b>-orientraw</b>, it can
+take a considerable amount of processing for <b>tifftopnm</b> to
+produce the output image.
+
+<p>You can use <b>pamflip</b> to turn the output into the image the
+TIFF stream represents.
+
+<p>With this option, <b>tifftopnm</b> always uses the Row By Row method
+(see <b>-byrow</b>).
+
+<p>This option was new in Netpbm 10.42 (March 2008).  Before that,
+<b>tifftopnm<b> generally produces arbitrary results with TIFF images
+that have an orientation other than the common one.
+
 <dt><b>-verbose</b>
 
 <dd>Print extra messages to Standard Error about the conversion.