Fixed: support for alpha with gray images in SGI format.

1 files changed, 16 insertions, 1 deletions

diff --git a/src/im_format_sgi.cpp b/src/im_format_sgi.cpp
index 08bbf4d..695340b 100644
--- a/src/im_format_sgi.cpp
+++ b/src/im_format_sgi.cpp
@@ -2,7 +2,7 @@
  * \brief SGI - Silicon Graphics Image File Format
  *
  * See Copyright Notice in im_lib.h
- * $Id: im_format_sgi.cpp,v 1.2 2008/12/03 15:45:34 scuri Exp $
+ * $Id: im_format_sgi.cpp,v 1.3 2011/01/19 16:28:59 scuri Exp $
  */
 
 #include "im_format.h"
@@ -300,9 +300,13 @@ int imFileFormatSGI::ReadImageInfo(int index)
   switch (dimension)
   {
   case 1:
+    // If this value is 1, the image file consists of only 1 channel and only 1 scanline (row).
+    // Only width is valid.
     this->height = 1;
     depth = 1;
   case 2:
+    // If this value is 2, the file consists of a single channel with a number of scanlines. 
+    // Only width and height are valid.
     depth = 1;
     break;
   case 3:
@@ -319,6 +323,10 @@ int imFileFormatSGI::ReadImageInfo(int index)
     case 1:
       this->file_color_mode = IM_GRAY;
       break;
+    case 2:
+      // This is NOT mentioned by the specification, but it is used
+      this->file_color_mode = IM_GRAY | IM_ALPHA;
+      break;
     case 3:
       this->file_color_mode = IM_RGB;
       break;
@@ -411,6 +419,13 @@ int imFileFormatSGI::WriteImageInfo()
     if (imColorModeHasAlpha(this->user_color_mode))
       this->file_color_mode |= IM_ALPHA;
   }
+  else if (this->file_color_mode == IM_GRAY &&
+           imColorModeHasAlpha(this->user_color_mode))
+  {
+    // This is NOT mentioned by the specification, but it is used
+    dimension = 3;
+    this->file_color_mode |= IM_ALPHA;
+  }
 
   this->file_data_type = this->user_data_type;