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First successful JBIG2 reprocessing

This commit is contained in:
John Whitington 2023-12-23 14:07:17 +00:00
parent fe34a7a752
commit 68312dc177
1 changed files with 28 additions and 14 deletions
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42
cpdfimage.ml
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@ -39,11 +39,13 @@ let pnm_to_channel_8 ch w h s =
done
done
let pnm_to_channel_1 ch w h s =
let pnm_to_channel_1_inverted ch w h s =
pnm_output_string ch "P4";
pnm_header ch w h;
pnm_newline ch;
pnm_output_string ch (Pdfio.string_of_bytes s)
let inverted = Pdfio.copybytes s in
Pdfio.bytes_selfmap lnot inverted;
pnm_output_string ch (Pdfio.string_of_bytes inverted)
let cmyk_to_channel_32 ch w h s =
let pos = ref 0 in
@ -488,17 +490,15 @@ let image_of_input fobj i =
let pdf, pageroot = Pdfpage.add_pagetree [page] pdf in
Pdfpage.add_root pageroot [] pdf
(* NOTE: ./cpdf -convert convert -recrypt -process-images -lossless-to-jpeg 65 ~/repos/pdfs/PDFTests/main128fail.pdf -o out.pdf *)
(* FIXME Only do if quality < 100 *)
(* FIXME Error when path_to_convert not defined *)
(* FIXME Need the "is it smaller" check from Pdfcodec.encode here too? *)
(* FIXME (this appears to make the file larger than ./cpdf ~/repos/pdfs/PDFTests/main128fail.pdf -recrypt -o out.pdf. Why? Seems to not create new object streams. Make it do so, since this a compression mechanism? An empty Pdf.objiter should not blow up a file like this!) *)
(* For each image xobject, process it through convert to reduce size. *)
(* FIXME What about predictors? Audit to see if files get smaller. *)
(* FIXME if lossy only 5% smaller, ignore? Set this parameter... *)
(* FIXME error handling for Sys.remove, others *)
(* FIXME Use raw format for all, and make it fast *)
(* FIXME combine path_to_im / path_to_convert *)
(* FIXME what are the best jbig2enc parameters *)
let jpeg_to_jpeg pdf ~q ~path_to_convert s dict reference =
Pdf.getstream s;
let out = Filename.temp_file "cpdf" "convertin" ^ ".jpg" in
@ -597,9 +597,7 @@ let lossless_to_jpeg pdf ~qlossless ~path_to_convert s dict reference =
print_string (Printf.sprintf "%s (%s) [%s]\n" colspace bpc filter);
() (* an image we cannot or do not handle *)
(* FIXME redirection on all platforms *)
let recompress_1bpp_jbig2_lossless ~path_to_jbig2enc pdf s dict reference =
Printf.printf "recompress_1bpp_jbig2_lossless\n";
let size = match Pdf.lookup_direct pdf "/Length" dict with Some (Pdf.Integer i) -> i | _ -> 0 in
Pdfcodec.decode_pdfstream_until_unknown pdf s;
begin match Pdf.lookup_direct pdf "/Filter" (fst !reference) with Some _ -> () | None ->
@ -609,17 +607,33 @@ let recompress_1bpp_jbig2_lossless ~path_to_jbig2enc pdf s dict reference =
let out2 = Filename.temp_file "cpdf" "convertout" ^ ".jbig2" in
let fh = open_out_bin out in
let data = match s with Pdf.Stream {contents = _, Pdf.Got d} -> d | _ -> assert false in
pnm_to_channel_1 fh w h data;
pnm_to_channel_1_inverted fh w h data;
close_out fh;
let retcode =
let command =
Filename.quote_command ~stdout:out2 path_to_jbig2enc ["-s"; "-p"; "-v"; out]
in
Printf.printf "%S\n" command; Sys.command command
let command = Filename.quote_command ~stdout:out2 path_to_jbig2enc ["-p"; out] in
(*Printf.printf "%S\n" command;*) Sys.command command
in
Printf.printf "retcode = %i\n" retcode
if retcode = 0 then
begin
let result = open_in_bin out2 in
let newsize = in_channel_length result in
if newsize < size then
begin
Printf.printf "1bpp to JBIG2 %i -> %i \n" size newsize;
reference :=
(Pdf.remove_dict_entry
(Pdf.add_dict_entry
(Pdf.add_dict_entry dict "/Length" (Pdf.Integer newsize))
"/Filter"
(Pdf.Name "/JBIG2Decode")) "/DecodeParms"),
Pdf.Got (Pdfio.bytes_of_input_channel result)
end;
close_in result
end;
(*Sys.remove out;
Sys.remove out2*)
end
(* 3. Call jbig2enc *)
(* 4. Read in result *)
(* 5. Set data and dictionary *)