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-pixel-threshold

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John Whitington
2023-12-24 13:54:21 +00:00
parent 91a7ffd371
commit 20b9f59b2f
3 changed files with 31 additions and 18 deletions
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15
cpdfcommand.ml
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@@ -525,7 +525,8 @@ type args =
mutable no_warn_rotate : bool;
mutable jpegquality : int;
mutable jpegqualitylossless : int;
mutable onebppmethod : string}
mutable onebppmethod : string;
mutable pixel_threshold : int}
let args =
{op = None;
@@ -651,7 +652,8 @@ let args =
no_warn_rotate = false;
jpegquality = 100;
jpegqualitylossless = 100;
onebppmethod = ""}
onebppmethod = "";
pixel_threshold = 25}
let reset_arguments () =
args.op <- None;
@@ -759,6 +761,7 @@ let reset_arguments () =
args.jpegquality <- 100;
args.jpegqualitylossless <- 100;
args.onebppmethod <- "";
args.pixel_threshold <- 0;
(* Do not reset original_filename or cpdflin or was_encrypted or
was_decrypted_with_owner or recrypt or producer or creator or path_to_* or
gs_malformed or gs_quiet or no-warn-rotate, since we want these to work
@@ -1938,6 +1941,9 @@ let setjpegqualitylossless q =
let set1bppmethod m =
args.onebppmethod <- m
let setpixelthreshold i =
args.pixel_threshold <- i
(* 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
@@ -2727,6 +2733,9 @@ and specs =
("-1bpp-method",
Arg.String set1bppmethod,
" Set 1bpp compression method for existing images");
("-pixel-threshold",
Arg.Int setpixelthreshold,
" Only process images with more pixels than this");
("-squeeze",
Arg.Unit setsqueeze,
" Squeeze");
@@ -4464,7 +4473,7 @@ let go () =
write_pdf false (Cpdfchop.chop ~x ~y ~columns:args.impose_columns ~btt:args.impose_btt ~rtl:args.impose_rtl pdf range)
| Some ProcessImages ->
let pdf = get_single_pdf args.op false in
Cpdfimage.process pdf ~q:args.jpegquality ~qlossless:args.jpegqualitylossless ~onebppmethod:args.onebppmethod ~path_to_jbig2enc:args.path_to_jbig2enc ~path_to_convert:args.path_to_convert;
Cpdfimage.process pdf ~q:args.jpegquality ~qlossless:args.jpegqualitylossless ~onebppmethod:args.onebppmethod ~pixel_threshold:args.pixel_threshold ~path_to_jbig2enc:args.path_to_jbig2enc ~path_to_convert:args.path_to_convert;
write_pdf false pdf
(* Advise the user if a combination of command line flags makes little sense,

32
cpdfimage.ml
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@@ -490,7 +490,10 @@ let image_of_input fobj i =
let pdf, pageroot = Pdfpage.add_pagetree [page] pdf in
Pdfpage.add_root pageroot [] pdf
let jpeg_to_jpeg pdf ~q ~path_to_convert s dict reference =
let jpeg_to_jpeg pdf ~pixel_threshold ~q ~path_to_convert s dict reference =
let w = match Pdf.lookup_direct pdf "/Width" dict with Some (Pdf.Integer i) -> i | _ -> error "bad width" in
let h = match Pdf.lookup_direct pdf "/Height" dict with Some (Pdf.Integer i) -> i | _ -> error "bad height" in
if w * h < pixel_threshold then () else
Pdf.getstream s;
let out = Filename.temp_file "cpdf" "convertin" ^ ".jpg" in
let out2 = Filename.temp_file "cpdf" "convertout" ^ ".jpg" in
@@ -531,16 +534,17 @@ let suitable_num pdf dict =
| Some (Pdf.Array (Pdf.Name "/Separation"::_)) -> ~-1
| _ -> 0
let lossless_to_jpeg pdf ~qlossless ~path_to_convert s dict reference =
let lossless_to_jpeg pdf ~pixel_threshold ~qlossless ~path_to_convert s dict reference =
let bpc = Pdf.lookup_direct pdf "/BitsPerComponent" dict in
let components = suitable_num pdf dict in
match components, bpc with
| (1 | 3 | 4 | -1), Some (Pdf.Integer 8) ->
let w = match Pdf.lookup_direct pdf "/Width" dict with Some (Pdf.Integer i) -> i | _ -> error "bad width" in
let h = match Pdf.lookup_direct pdf "/Height" dict with Some (Pdf.Integer i) -> i | _ -> error "bad height" in
if w * h < pixel_threshold then () else
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 ->
let w = match Pdf.lookup_direct pdf "/Width" dict with Some (Pdf.Integer i) -> i | _ -> error "bad width" in
let h = match Pdf.lookup_direct pdf "/Height" dict with Some (Pdf.Integer i) -> i | _ -> error "bad height" in
let out = Filename.temp_file "cpdf" "convertin" ^ (if suitable_num pdf dict < 4 then ".pnm" else ".cmyk") in
let out2 = Filename.temp_file "cpdf" "convertout" ^ ".jpg" in
let fh = open_out_bin out in
@@ -578,23 +582,23 @@ let lossless_to_jpeg pdf ~qlossless ~path_to_convert s dict reference =
Sys.remove out2
end
| colspace, bpc ->
let colspace = Pdf.lookup_direct pdf "/ColorSpace" dict in
(*let colspace = Pdf.lookup_direct pdf "/ColorSpace" dict in
let colspace, bpc, filter =
(match colspace with None -> "none" | Some x -> Pdfwrite.string_of_pdf x),
(match bpc with None -> "none" | Some x -> Pdfwrite.string_of_pdf x),
(match Pdf.lookup_direct pdf "/Filter" dict with None -> "none" | Some x -> Pdfwrite.string_of_pdf x)
in
print_string (Pdfwrite.string_of_pdf dict);
print_string (Printf.sprintf "%s (%s) [%s]\n" colspace bpc filter);
print_string (Printf.sprintf "%s (%s) [%s]\n" colspace bpc filter);*)
() (* an image we cannot or do not handle *)
let recompress_1bpp_jbig2_lossless ~path_to_jbig2enc pdf s dict reference =
let recompress_1bpp_jbig2_lossless ~pixel_threshold ~path_to_jbig2enc pdf s dict reference =
let w = match Pdf.lookup_direct pdf "/Width" dict with Some (Pdf.Integer i) -> i | _ -> error "bad width" in
let h = match Pdf.lookup_direct pdf "/Height" dict with Some (Pdf.Integer i) -> i | _ -> error "bad height" in
if w * h < pixel_threshold then () else (* jbig2enc fails on tiny images *)
let size = match Pdf.lookup_direct pdf "/Length" dict with Some (Pdf.Integer i) -> i | _ -> 0 in
Pdfcodec.decode_pdfstream_until_unknown pdf s;
match Pdf.lookup_direct pdf "/Filter" (fst !reference) with Some _ -> () | None ->
let w = match Pdf.lookup_direct pdf "/Width" dict with Some (Pdf.Integer i) -> i | _ -> error "bad width" in
let h = match Pdf.lookup_direct pdf "/Height" dict with Some (Pdf.Integer i) -> i | _ -> error "bad height" in
if w < 5 || h < 5 then () else (* jbig2enc fails on tiny images *)
let out = Filename.temp_file "cpdf" "convertin" ^ ".pnm" in
let out2 = Filename.temp_file "cpdf" "convertout" ^ ".jbig2" in
let fh = open_out_bin out in
@@ -628,7 +632,7 @@ let recompress_1bpp_jbig2_lossless ~path_to_jbig2enc pdf s dict reference =
(* JPEG to JPEG: RGB and CMYK JPEGS *)
(* Lossless to JPEG: 8bpp Grey, 8bpp RGB, 8bpp CMYK including separation and ICCBased colourspaces *)
(* 1 bit: anything to JBIG2 lossless (no globals) *)
let process ?q ?qlossless ?onebppmethod pdf ~path_to_jbig2enc ~path_to_convert =
let process ?q ?qlossless ?onebppmethod ~pixel_threshold pdf ~path_to_jbig2enc ~path_to_convert =
let process_obj _ s =
match s with
| Pdf.Stream ({contents = dict, _} as reference) ->
@@ -640,18 +644,18 @@ let process ?q ?qlossless ?onebppmethod pdf ~path_to_jbig2enc ~path_to_convert =
with
| Some (Pdf.Name "/Image"), Some (Pdf.Name "/DCTDecode" | Pdf.Array [Pdf.Name "/DCTDecode"]), _, _ ->
begin match q with
| Some q -> jpeg_to_jpeg pdf ~q ~path_to_convert s dict reference
| Some q -> jpeg_to_jpeg pdf ~pixel_threshold ~q ~path_to_convert s dict reference
| None -> ()
end
| Some (Pdf.Name "/Image"), _, Some (Pdf.Integer 1), _
| Some (Pdf.Name "/Image"), _, _, Some (Pdf.Boolean true) ->
begin match onebppmethod with
| Some "JBIG2" -> recompress_1bpp_jbig2_lossless ~path_to_jbig2enc pdf s dict reference
| Some "JBIG2" -> recompress_1bpp_jbig2_lossless ~pixel_threshold ~path_to_jbig2enc pdf s dict reference
| _ -> ()
end
| Some (Pdf.Name "/Image"), _, _, _ ->
begin match qlossless with
| Some qlossless -> lossless_to_jpeg pdf ~qlossless ~path_to_convert s dict reference
| Some qlossless -> lossless_to_jpeg pdf ~pixel_threshold ~qlossless ~path_to_convert s dict reference
| None -> ()
end
| _ -> () (* not an image *)

2
cpdfimage.mli
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@@ -11,7 +11,7 @@ val image_resolution : Pdf.t -> int list -> float -> (int * string * int * int *
(** List images in JSON format *)
val images : Pdf.t -> int list -> Cpdfyojson.Safe.t
val process : ?q:int -> ?qlossless:int -> ?onebppmethod:string -> Pdf.t -> path_to_jbig2enc:string -> path_to_convert:string -> unit
val process : ?q:int -> ?qlossless:int -> ?onebppmethod:string -> pixel_threshold:int -> Pdf.t -> path_to_jbig2enc:string -> path_to_convert:string -> unit
(**/**)
val image_of_input : (unit -> Pdfio.bytes -> Pdf.pdfobject * (int * Pdf.pdfobject) list) -> Pdfio.input -> Pdf.t