diff --git a/MANUAL.txt b/MANUAL.txt
index 5c592bcea..98970c14f 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -733,9 +733,12 @@ header when requesting a document from a URL:
 
 `--dpi`=*NUMBER*
 
-:   Specify the dpi (dots per inch) value for conversion from pixels
-    to inch/centimeters and vice versa. The default is 96dpi.
-    Technically, the correct term would be ppi (pixels per inch).
+:   Specify the default dpi (dots per inch) value for conversion
+    from pixels to inch/centimeters and vice versa. (Technically,
+    the correct term would be ppi: pixels per inch.) The default
+    is 96dpi.   When images contain information about dpi
+    internally, the encoded value is used instead of the default
+    specified by this option.
 
 `--wrap=auto`|`none`|`preserve`