diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index 017c509..bbd29fa 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -231,7 +231,7 @@ type op =
   | SetLanguage of string
   | Redact
   | Rasterize
-  | OutputImage of string
+  | OutputImage
 
 let string_of_op = function
   | PrintFontEncoding _ -> "PrintFontEncoding"
@@ -386,7 +386,7 @@ let string_of_op = function
   | SetLanguage _ -> "SetLanguage"
   | Redact -> "Redact"
   | Rasterize -> "Rasterize"
-  | OutputImage _ -> "OutputImage"
+  | OutputImage -> "OutputImage"
 
 (* Inputs: filename, pagespec. *)
 type input_kind = 
@@ -948,7 +948,7 @@ let banned banlist = function
   | OCGRename | OCGList | OCGOrderAll | PrintFontEncoding _ | TableOfContents | Typeset _ | Composition _
   | TextWidth _ | SetAnnotations _ | CopyAnnotations _ | ExtractStream _ | PrintObj _ | ReplaceObj _
   | Verify _ | MarkAs _ | RemoveMark _ | ExtractStructTree | ReplaceStructTree _ | SetLanguage _
-  | PrintStructTree | Rasterize | OutputImage _
+  | PrintStructTree | Rasterize | OutputImage
      -> false (* Always allowed *)
   (* Combine pages is not allowed because we would not know where to get the
   -recrypt from -- the first or second file? *)
@@ -3022,7 +3022,7 @@ let specs =
    ("-rasterize-no-antialias", Arg.Unit (fun () -> args.rast_antialias <- false), " Don't antialias when rasterizing");
    ("-rasterize-downsample", Arg.Unit (fun () -> args.rast_downsample <- true), " Antialias by downsampling");
    ("-rasterize-jpeg-quality", Arg.Int (fun i -> args.rast_jpeg_quality <- i), " Set JPEG quality");
-   ("-output-image", Arg.String (fun s -> args.op <- Some (OutputImage s)), " Output pages as PNGs");
+   ("-output-image", Arg.Unit (fun () -> args.op <- Some OutputImage), " Output pages as images");
    (* These items are undocumented *)
    ("-debug", Arg.Unit setdebug, "");
    ("-debug-crypt", Arg.Unit (fun () -> args.debugcrypt <- true), "");
@@ -4894,7 +4894,8 @@ let go () =
       let pdf = get_single_pdf args.op false in
       let range = parse_pagespec_allow_empty pdf (get_pagespec ()) in
         write_pdf false (rasterize args.rast_antialias args.rast_downsample args.rast_device args.rast_res args.rast_annots args.rast_jpeg_quality pdf range)
-  | Some (OutputImage spec) ->
+  | Some OutputImage ->
+      let spec = match args.out with File spec -> spec | _ -> error "Output must be to a file" in
       let pdf = get_single_pdf args.op false in
       let range = parse_pagespec_allow_empty pdf (get_pagespec ()) in
         write_images args.rast_device args.rast_res args.rast_jpeg_quality args.tobox args.rast_annots args.rast_antialias args.rast_downsample spec pdf range
diff --git a/cpdfmanual.pdf b/cpdfmanual.pdf
index 3df3993..d57225f 100644
Binary files a/cpdfmanual.pdf and b/cpdfmanual.pdf differ
diff --git a/cpdfmanual.tex b/cpdfmanual.tex
index 23bd4d9..06bb83e 100644
--- a/cpdfmanual.tex
+++ b/cpdfmanual.tex
@@ -3837,7 +3837,7 @@ The \texttt{-dump-attachments} operation, when given a PDF file and a directory
 
 \vspace{1.5mm}
 
-\noindent\small\verb!cpdf -output-image <format> in.pdf <range>!\\
+\noindent\small\verb!cpdf -output-image in.pdf <range> -o <format>!\\
 \noindent\small\verb!     [-rasterize[-gray|-1bpp|-jpeg|-jpeggray]!\\
 \noindent\small\verb!     [-rasterize-res <n>] [-rasterize-jpeg-quality <n>]!\\
 \noindent\small\verb!     [-rasterize-no-antialias | -rasterize-downsample]!
@@ -4085,7 +4085,7 @@ Option & Effect\\\hline
 \noindent In addition to rasterization of pages, we can export them in PNG or JPEG format, again by the use of GhostScript:
 
   \begin{framed}
-  \noindent\small\verb!cpdf -gs gs -output-image image%%%.png in.pdf 10-end!
+  \noindent\small\verb!cpdf -gs gs -output-image in.pdf 10-end -o image%%%.png!
   \end{framed}
 
 \noindent This will extract pages 10 onwards to the files \texttt{image000.png}, \texttt{image001.png} and so on. All the options above apply, and in addition we can choose which box is rasterized:
@@ -4100,8 +4100,8 @@ Option & Effect\\\hline
 \noindent For example:
 
   \begin{framed}
-  \noindent\small\verb!cpdf -gs gs -output-image image%%%.jpeg -tobox /BleedBox!\\
-  \noindent\small\verb!     -rasterization-jpeg in.pdf!
+  \noindent\small\verb!cpdf -gs gs -output-image -tobox /BleedBox!\\
+  \noindent\small\verb!     -rasterization-jpeg in.pdf -o image%%%.jpeg!
   \end{framed}