[GRASS-SVN] r29918 - grass/trunk/raster/r.compress
svn_grass at osgeo.org
svn_grass at osgeo.org
Thu Jan 31 22:25:50 EST 2008
Date: 2008-01-31 22:25:50 -0500 (Thu, 31 Jan 2008)
New Revision: 29918
Updated old terminology and module descriptions; standardized section headings
--- grass/trunk/raster/r.compress/description.html 2008-02-01 02:42:15 UTC (rev 29917)
+++ grass/trunk/raster/r.compress/description.html 2008-02-01 03:25:50 UTC (rev 29918)
@@ -1,6 +1,5 @@
The GRASS program <EM>r.compress</EM> can be used to compress and decompress
raster map layers.
@@ -13,11 +12,12 @@
reduced in size. Some raster map layers are shrunk to
roughly 1% of their original sizes. Raster map layers
containing complex images such as elevation and photo or
-satellite images may increase slightly in size. GRASS uses
-a new compressed format, and all new raster maps are now
-automatically stored in compressed form (see FORMATS
-below). GRASS programs can read both compressed and
-regular (uncompressed) file formats. This allows the use
+satellite images may increase slightly in size.
+<!-- The 'new compressed format' probably isn't new anymore as of 2008. - EP
+GRASS uses a new compressed format, -->
+All new raster maps are now automatically stored in compressed
+form (see FORMATS below). GRASS programs can read both compressed
+and regular (uncompressed) file formats. This allows the use
of whichever raster data format consumes less space.
@@ -30,14 +30,13 @@
Raster files may be decompressed to return them to their
-original format, using the <B>-u</B> option of
+original format, using the <B>-u</B> flag of
<EM>r.compress</EM>. If <EM>r.compress</EM> is asked to
compress a raster map which is already compressed (or to
-decompress an already decompressed file), it simply informs
-the user of this and asks the user if he wishes to perform
-the reverse operation.
+decompress an already decompressed raster map), it simply informs
+the user the map is already (de)compressed and exits.
<EM>r.compress</EM> can be run either non-interactively or
interactively. In non-interactive use, the user must
@@ -45,26 +44,11 @@
compressed (or decompressed) on the command line, using the
form <B>map=</B><EM>name</EM>[,<EM>name</EM>,...] (where
each <EM>name</EM> is the name of a raster map layer to be
-compressed or decompressed). To decompress a map, the user
-must include the <B>-u</B> option on the command line. If
-the <B>-u</B> option is not included on the command line,
-<EM>r.compress</EM> will attempt to compress the named map
+compressed or decompressed). The default behavior is to
+compress the named map(s).
-If the user simply types <B>r.compress</B> without specifying any
-map layer name(s) on the command line,
-<EM>r.compress</EM> will prompt the user for the names of the map layers
-to be compressed/decompressed, and ask whether these maps are to be
-compressed or decompressed.
-If the <B>-u</B> flag is set, <EM>r.compress</EM> converts a compressed map
-to its <EM>uncompressed</EM> format. If not set, <EM>r.compress</EM> will
-attempt to compress the named map layer(s).
Conceptually, a raster data file consists of rows of cells,
with each row containing the same number of cells. A cell
consists of one or more bytes. The number of bytes per
@@ -103,7 +87,7 @@
automatically used when new raster map layers are
First 3 bytes (chars) - These are a special code that identifies
the raster data as compressed.
@@ -124,7 +108,7 @@
255) of the number of cells that contain the category
values given by the remaining bytes of the group.
The 3 byte code is not used.
Instead, a field in the cell header is used to indicate compressed format.
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