Mini Shell

%!
% 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 (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
        }{
          (ColorConversionStrategy not a device space, falling back to ProcessColorModel, output may not be valid PDF/A.)=
          true
        } ifelse
      } ifelse
    } ifelse
  } {
    (ColorConversionStrategy not set, falling back to ProcessColorModel, output may not be valid PDF/A.)=
    true
  } ifelse

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

>> /PUT pdfmark
[{icc_PDFA} ICCProfile (r) file /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