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JBIG2 extraction done

This commit is contained in:
John Whitington 2023-12-04 11:19:17 +00:00
parent 65e5b391e2
commit eefbb4f315
2 changed files with 34 additions and 1 deletions
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@ -17,6 +17,7 @@ Extended features:
o -list-images-used[-json] extends -image-resolution
o Use -raw with -extract-images to get PNMs
o -extract-images can extract JBIG2 images and their globals
Fixes:

34
cpdfimage.ml
View File

@ -27,11 +27,41 @@ let write_stream name stream =
Pdfio.bytes_to_output_channel fh stream;
close_out fh
let jbig2_serial = ref 0
let jbig2_globals = null_hash ()
let write_image ~raw ?path_to_p2p ?path_to_im pdf resources name image =
match Pdfimage.get_image_24bpp pdf resources image with
| Pdfimage.JPEG (stream, _) -> write_stream (name ^ ".jpg") stream
| Pdfimage.JPEG2000 (stream, _) -> write_stream (name ^ ".jpx") stream
| Pdfimage.JBIG2 (stream, _) -> write_stream (name ^ ".jbig2") stream
| Pdfimage.JBIG2 (stream, _, global) ->
begin match global with
| None ->
Printf.printf "JBIG2: No global, writing plain\n";
write_stream (name ^ ".jbig2") stream
| Some g ->
Printf.printf "JBIG2: there is a global\n";
let go () =
let serial, _ = Hashtbl.find jbig2_globals g in
write_stream (name ^ ".jbig2__" ^ string_of_int serial) stream
in
try go () with Not_found ->
jbig2_serial += 1;
let globaldata =
let obj = Pdf.lookup_obj pdf g in
Pdfcodec.decode_pdfstream_until_unknown pdf obj;
match obj with | Pdf.Stream {contents = (_, Got b)} -> Some b | _ -> None
in
match globaldata with
| Some d ->
Hashtbl.add jbig2_globals g (!jbig2_serial, d);
let filename = Filename.concat (Filename.dirname name) (string_of_int !jbig2_serial ^ ".jbig2global") in
write_stream filename d;
go ()
| None ->
Pdfe.log "Could not extract JBIG2Globals. Skipping this image."
end
| Pdfimage.Raw (w, h, Pdfimage.BPP24, stream) ->
let pnm = name ^ ".pnm" in
let png = name ^ ".png" in
@ -99,6 +129,8 @@ let rec extract_images_form_xobject ~raw ?path_to_p2p ?path_to_im encoding dedup
extract_images_inner ~raw ?path_to_p2p ?path_to_im encoding serial pdf resources stem pnum images
let extract_images ?(raw=false) ?path_to_p2p ?path_to_im encoding dedup dedup_per_page pdf range stem =
Hashtbl.clear jbig2_globals;
jbig2_serial := 0;
if dedup || dedup_per_page then written := [];
let pdf_pages = Pdfpage.pages_of_pagetree pdf in
let pages =