adding constants for the geotiff names and including the concept of 4 and 5 channel geotiffs

git-svn-id: https://svn.ssec.wisc.edu/repos/glance/trunk@226 8a9318a1-56ba-4d59-b755-99d26321be01

pyglance/glance/io.py

@@ -988,19 +988,54 @@ class tiff (object):
     
     _tiff = None
     
+    GRAY_NAME  = "grayscale value"
+    RED_NAME   = "red"
+    GREEN_NAME = "green"
+    BLUE_NAME  = "blue"
+    IR_NAME    = "infrared"
+    ALPHA_NAME = "alpha"
+    
+    
     # if we are using meaningful names, we will translate between
     # the band index numbers and these names (otherwise bands use generic names)
     EXPECTED_BAND_NAME_KEY = {
-                                1: ["grayscale value"],
-                                3: ["red", "green", "blue"],
-                                4: ["red", "green", "blue", "alpha"],
+                                1: [GRAY_NAME],
+                                2: [GRAY_NAME, ALPHA_NAME],
+                                3: [RED_NAME, GREEN_NAME, BLUE_NAME],
+                                4: [RED_NAME, GREEN_NAME, BLUE_NAME, ALPHA_NAME],
+                                5: [RED_NAME, GREEN_NAME, BLUE_NAME, IR_NAME, ALPHA_NAME],
                              }
-    SPECIAL_NAMES_TO_IDX   =  {
-                                "grayscale value":  1,
-                                "red":              1,
-                                "green":            2,
-                                "blue":             3,
-                                "alpha":            4,
+    
+    # a reverse look up to help disambigurate what meaningful name goes with
+    # which number (one of these dictionaries will be selected based on the
+    # number of bands in the geotiff)
+    REV_INFO               = {
+                                1: {
+                                    GRAY_NAME:  1,
+                                    },
+                                2: {
+                                    GRAY_NAME:  1,
+                                    ALPHA_NAME: 2,
+                                    },
+                                3: {
+                                    RED_NAME:   1,
+                                    GREEN_NAME: 2,
+                                    BLUE_NAME:  3,
+                                    },
+                                4: {
+                                    RED_NAME:   1,
+                                    GREEN_NAME: 2,
+                                    BLUE_NAME:  3,
+                                    ALPHA_NAME: 4,
+                                    },
+                                5: {
+                                    RED_NAME:   1,
+                                    GREEN_NAME: 2,
+                                    BLUE_NAME:  3,
+                                    IR_NAME:    4,
+                                    ALPHA_NAME: 5,
+                                    },
+                                
                               }
     
     def _get_generic_band_name (self, number) :
@@ -1012,14 +1047,14 @@ class tiff (object):
         """get an index for the band from a name
         
         name may be either a meaningful name from the list that shows
-        up in SPECIAL_NAMES_TO_IDX's keys or a generic name that was
+        up in the reverse index keys or a generic name that was
         generated by _get_generic_band_name
         """
         
         to_return = None
         
-        if name in self.SPECIAL_NAMES_TO_IDX.keys() :
-            to_return = self.SPECIAL_NAMES_TO_IDX[name]
+        if name in self.revIndex.keys() :
+            to_return = self.revIndex[name]
         else :
             to_return = int(name.split(' ')[-1])
         
@@ -1036,6 +1071,7 @@ class tiff (object):
         
         self._tiff     = gdal.Open(filename)
         self.niceNames = useMeaningfulNames
+        self.revIndex  = self.REV_INFO[self._tiff.RasterCount]
 
     def __call__(self):
         "yield names of variables to be compared"
@@ -1155,7 +1191,9 @@ class tiff (object):
         return True
 
 # people also name tiff files with one f...
-tif = tiff
+tif  = tiff
+# Nick has special tiff files with alpha...
+tifa = tiff
 
 def _search_xml(pathname):
     xs = '.xml'