Python调用Ghostscript转PDF/A遇验证失败，求合规方案及版本指定方法

我尝试通过Python子进程执行Ghostscript命令，将PDF文件转换为PDF/A归档格式，但生成的文件无法通过验证。当前使用的Ghostscript命令如下：

gs -dPDFA=3 -dBATCH -dNOPAUSE -dNOSAFER -sColorConversionStrategy=UseDeviceIndependentColor -sDEVICE=pdfwrite -dPDFACompatibilityPolicy=3 -dPDFACompatibilityLevel=3u -sOutputFile=dummypdfa.pdf dummy.pdf 

虽然成功生成了dummypdfa.pdf，但该文件无法通过在线验证工具的检测。我刚接触Ghostscript，希望得到无需依赖REST API封装的转换方案。

补充：ICC配置文件对应的前缀代码 #

我使用的sRGB.icc配置文件对应的前缀PostScript代码如下：

%!
% This is a sample prefix file for creating a PDF/A document.
% Users should modify entries marked with "Customize".
% This assumes an ICC profile resides in the file (srgb.icc),
% in the current directory unless the user modifies the corresponding line below.

% Define entries in the document Info dictionary :
[ /Title (Title)       % Customise
  /DOCINFO pdfmark

% Define an ICC profile :
/ICCProfile (D:/scripts/2024/upwork/PDF2PDF-A/sRGB.icc) % Customise
def

[/_objdef {icc_PDFA} /type /stream /OBJ pdfmark

%% This code attempts to set the /N (number of components) key for the ICC colour space.
%% To do this it checks the ColorConversionStrategy or the device ProcessColorModel if
%% ColorConversionStrategy is not set.
%% This is not 100% reliable. A better solution is for the user to edit this and replace
%% the code between the ---8<--- lines with a simple declaration like:
%%   /N 3
%% where the value of N is the number of components from the profile defined in /ICCProfile above.
%%
[{icc_PDFA}
<<
%% ----------8<--------------8<-------------8<--------------8<----------
  systemdict /ColorConversionStrategy known {
    systemdict /ColorConversionStrategy get cvn dup /Gray eq {
      pop /N 1 false
    }{
      dup /RGB eq {
        pop /N 3 false
      }{
        /CMYK eq {
          /N 4 false
        }{
          (\tColorConversionStrategy not a device space, falling back to ProcessColorModel, output may not be valid PDF/A.\n)=
          true
        } ifelse
      } ifelse
    } ifelse
  } {
    (\tColorConversionStrategy not set, falling back to ProcessColorModel, output may not be valid PDF/A.\n)=
    true
  } ifelse

  {
    currentpagedevice /ProcessColorModel get
    dup /DeviceGray eq {
      pop /N 1
    }{
      dup /DeviceRGB eq {
        pop /N 3
      }{
        dup /DeviceCMYK eq {
          pop /N 4
        } {
          (\tProcessColorModel not a device space.)=
          /ProcessColorModel cvx /rangecheck signalerror
        } ifelse
      } ifelse
    } ifelse
  } if
%% ----------8<--------------8<-------------8<--------------8<----------

>> /PUT pdfmark
[
{icc_PDFA}
{ICCProfile (r) file} stopped
{
  (\n\tFailed to open the supplied ICCProfile for reading. This may be due to\n) print
  (\t  an incorrect filename or a failure to add --permit-file-read=<profile>\n) print
  (\t  to the command line. This PostScript program needs to open the file\n) print
  (\t  and you must explicitly grant it permission to do so.\n\n) print
  (\tPDF/A processing aborted, output may not be a PDF/A file.\n\n) print
  cleartomark
}
{
  /PUT pdfmark
  % Define the output intent dictionary :

  [/_objdef {OutputIntent_PDFA} /type /dict /OBJ pdfmark
  [{OutputIntent_PDFA} <<
    /Type /OutputIntent               % Must be so (the standard requires).
    /S /GTS_PDFA1                     % Must be so (the standard requires).
    /DestOutputProfile {icc_PDFA}     % Must be so (see above).
    /OutputConditionIdentifier (sRGB) % Customize
  >> /PUT pdfmark
  [{Catalog} << /OutputIntents [ {OutputIntent_PDFA} ] >> /PUT pdfmark
} ifelse

额外疑问 #

是否可以通过Ghostscript指定转换为不同版本的PDF/A？比如PDF/A-1a、2a、2b、2u、3u这类具体版本？

内容的提问来源于stack exchange，提问作者John Kiruba