Add debug output for image processing

cpdfcommand.ml

@@ -1956,6 +1956,9 @@ let setlengththreshold i =
 let setpercentagethreshold i =
   args.percentage_threshold <- i
 
+let setprocessimagesinfo () =
+  set Cpdfimage.debug_image_processing
+
 (* Parse a control file, make an argv, and then make Arg parse it. *)
 let rec make_control_argv_and_parse filename =
   control_args := !control_args @ parse_control_file filename
@@ -2730,6 +2733,9 @@ and specs =
    ("-process-images",
      Arg.Unit (setop ProcessImages),
      " Process images within PDF");
+   ("-process-images-info",
+     Arg.Unit setprocessimagesinfo,
+     " Show info when processing images");
    ("-convert",
      Arg.String setconvertpath,
      " Path to convert executable");

cpdfimage.ml

@@ -2,6 +2,8 @@ open Pdfutil
 open Pdfio
 open Cpdferror
 
+let debug_image_processing = ref false
+
 let pnm_white ch = output_char ch ' '
 let pnm_newline ch = output_char ch '\n'
 let pnm_output_string = Stdlib.output_string
@@ -528,7 +530,7 @@ let jpeg_to_jpeg pdf ~pixel_threshold ~length_threshold ~percentage_threshold ~q
         let result = open_in_bin out2 in
         let newsize = in_channel_length result in
         if newsize < size then
-          (*Printf.printf "JPEG to JPEG %i -> %i\n" size newsize;*)
+          if !debug_image_processing then Printf.printf "JPEG to JPEG %i -> %i\n%!" size newsize;
           reference := Pdf.add_dict_entry dict "/Length" (Pdf.Integer newsize), Pdf.Got (Pdfio.bytes_of_input_channel result)
       end;
     Sys.remove out;
@@ -584,7 +586,7 @@ let lossless_to_jpeg pdf ~pixel_threshold ~length_threshold ~percentage_threshol
             let newsize = in_channel_length result in
             if newsize < size then
               begin
-                (*Printf.printf "Lossless to JPEG %i -> %i (components %i) \n" size newsize components;*)
+                if !debug_image_processing then Printf.printf "Lossless to JPEG %i -> %i\n%!" size newsize;
                 reference :=
                   (Pdf.add_dict_entry
                     (Pdf.add_dict_entry dict "/Length" (Pdf.Integer newsize))
@@ -632,7 +634,7 @@ let recompress_1bpp_jbig2_lossless ~pixel_threshold ~length_threshold ~path_to_j
             let newsize = in_channel_length result in
             if newsize < size then
               begin
-                (*Printf.printf "1bpp to JBIG2 %i -> %i \n" size newsize;*)
+                if !debug_image_processing then Printf.printf "1bpp to JBIG2 %i -> %i\n%!" size newsize;
                 reference :=
                   (Pdf.remove_dict_entry
                   (Pdf.add_dict_entry
@@ -653,7 +655,7 @@ let process
   ?q ?qlossless ?onebppmethod ~length_threshold ~percentage_threshold ~pixel_threshold
   ~path_to_jbig2enc ~path_to_convert pdf
 =
-  let process_obj _ s =
+  let process_obj objnum s =
     match s with
     | Pdf.Stream ({contents = dict, _} as reference) ->
         begin match
@@ -663,6 +665,7 @@ let process
           Pdf.lookup_direct pdf "/ImageMask" dict
         with
         | Some (Pdf.Name "/Image"), Some (Pdf.Name "/DCTDecode" | Pdf.Array [Pdf.Name "/DCTDecode"]), _, _ ->
+            if !debug_image_processing then Printf.printf "Object %i (JPEG)...\n%!" objnum;
             begin match q with
             | Some q ->
                 if q < 100 then jpeg_to_jpeg pdf ~pixel_threshold ~length_threshold ~percentage_threshold ~q ~path_to_convert s dict reference
@@ -670,12 +673,14 @@ let process
             end
         | Some (Pdf.Name "/Image"), _, Some (Pdf.Integer 1), _
         | Some (Pdf.Name "/Image"), _, _, Some (Pdf.Boolean true) ->
+            if !debug_image_processing then Printf.printf "Object %i (1bpp)...\n%!" objnum;
             begin match onebppmethod with
             | Some "JBIG2" ->
                 recompress_1bpp_jbig2_lossless ~pixel_threshold ~length_threshold ~path_to_jbig2enc pdf s dict reference
             | _ -> ()
             end
         | Some (Pdf.Name "/Image"), _, _, _ ->
+            if !debug_image_processing then Printf.printf "Object %i (lossless)...\n%!" objnum;
             begin match qlossless with
             | Some qlossless ->
                 if qlossless < 101 then lossless_to_jpeg pdf ~pixel_threshold ~length_threshold ~percentage_threshold ~qlossless ~path_to_convert s dict reference

cpdfimage.mli

@@ -1,5 +1,8 @@
 (** Images *)
 
+(** Print info when processing image *)
+val debug_image_processing : bool ref
+
 (** Extract images. *)
 val extract_images :
   ?raw:bool -> ?path_to_p2p:string -> ?path_to_im:string ->