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Preparing to fix lossless resample

This commit is contained in:
John Whitington 2024-02-19 17:56:35 +00:00
parent 24b905bf3f
commit cb396215c3
1 changed files with 9 additions and 3 deletions
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12
cpdfimage.ml
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@ -540,9 +540,10 @@ let jpeg_to_jpeg pdf ~pixel_threshold ~length_threshold ~percentage_threshold ~q
let suitable_num pdf dict =
match Pdf.lookup_direct pdf "/ColorSpace" dict with
| Some (Pdf.Name "/DeviceRGB") -> 3
| Some (Pdf.Name "/DeviceGray") -> 1
| Some (Pdf.Name ("/DeviceRGB" | "/CalRGB")) -> 3
| Some (Pdf.Name ("/DeviceGray" | "/CalGray")) -> 1
| Some (Pdf.Name "/DeviceCMYK") -> 4
| Some (Pdf.Array [Pdf.Name "/Lab"; _]) -> 3
| Some (Pdf.Array [Pdf.Name "/ICCBased"; stream]) ->
begin match Pdf.lookup_direct pdf "/N" stream with
| Some (Pdf.Integer 3) -> 3
@ -628,6 +629,7 @@ let lossless_to_jpeg pdf ~pixel_threshold ~length_threshold ~percentage_threshol
remove out2
let lossless_resample pdf ~pixel_threshold ~length_threshold ~factor ~interpolate ~path_to_convert s dict reference =
Printf.printf "***lossless_resample IN dictionary: %S\n" (Pdfwrite.string_of_pdf dict);
match lossless_out pdf ~pixel_threshold ~length_threshold ".png" s dict reference with
| None -> ()
| Some (_, _, _, 4, _, _) -> Printf.printf "lossless resampling for CMYK not supported yet\n%!"
@ -653,7 +655,11 @@ let lossless_resample pdf ~pixel_threshold ~length_threshold ~factor ~interpolat
reference :=
(match fst (obj_of_png_data (Pdfio.bytes_of_input_channel result)) with
| Pdf.Stream {contents = Pdf.Dictionary d, data} ->
let d' = fold_right (fun (k, v) d -> add k v d) d (match dict with Pdf.Dictionary x -> x | _ -> []) in
(* Find components of resultant colourspace, and bits per component. If differing from input, abandon *)
(* We will then test all the files we have available, and make sure all results correct *)
(* Then we will see about how to poke convert to do the correct thing - e.g not use PNG, force different output etc. *)
let d' = fold_right (fun (k, v) d -> if k <> "/ColorSpace" then add k v d else d) d (match dict with Pdf.Dictionary x -> x | _ -> []) in
Printf.printf "***lossless_resample OUT dictionary: %S\n" (Pdfwrite.string_of_pdf (Pdf.Dictionary d'));
(Pdf.Dictionary d', data)
| _ -> assert false)
end