J'ai trouvé une solution. Je vous donne la partie la plus importante du code de solution:
public enum DPIResolution {DPI72, DPI150, DPI300, DPI300PLUS}
// Program paths
public static final String PROGRAM_GSWIN64C_PATH = "C:/gs/gs9.16/bin/gswin64c.exe";
public static final String PROGRAM_GSWIN64C_OLD_PATH = "C:/gs/gs9.07/bin/gswin64c.exe";
public static final String PS_TMP_PATH = "D:/tmp.ps";
// Convert PDF Color to PDF Gray
private static int convertPDFColorToPDFGray(String inputPath, String outputPath, DPIResolution dpiResolution){
String[] cmd = {
PROGRAM_GSWIN64C_PATH, "-sDEVICE=pdfwrite", "-dPDFSETTINGS=/" + dpiForGS,
"-sColorConversionStrategy=Gray", "-sColorConversionStrategyForImages=Gray", "-sProcessColorModel=DeviceGray",
"-dCompatibilityLevel=1.4", "-dNOPAUSE", "-dBATCH",
"-sOutputFile=" + outputPath, inputPath, "-c", "quit"
};
int exitCode = ghostScriptCommand(cmd);
}
// Convert PDF Color to PDF Black and White
private static int convertPDFColorToPDFBlackAndWhite(String inputPath, String outputPath){
String[] cmd = {
PROGRAM_GSWIN64C_OLD_PATH, "-sDEVICE=psmono", "-dNOPAUSE", "-dBATCH",
"-sOutputFile=" + PS_TMP_PATH, inputPath, "-c", "quit"
};
String[] cmd2 = {
PROGRAM_GSWIN64C_PATH, "-sDEVICE=pdfwrite", "-dNOPAUSE", "-dBATCH",
"-sOutputFile=" + outputPath, PS_TMP_PATH, "-c", "quit"
};
int exitCode = ghostScriptCommand(cmd);
exitCode = ghostScriptCommand(cmd2);
// We remove the PS tmp file
File file = new File(PS_TMP_PATH);
try{
if(!file.delete()) System.out.println("Erreur de suppression de " + file.getName());
} catch(Exception e){
System.err.println("Erreur: " + e.getMessage());
e.printStackTrace();
}
};
// Command to Ghost Script (GS)
private static int ghostScriptCommand(String[] cmd){
try {
Process process = Runtime.getRuntime().exec(cmd);
int exitCode = process.waitFor();
// read the output from the command
String s;
BufferedReader stdInput = new BufferedReader(new InputStreamReader(process.getInputStream()));
String stringstdInput = "- Standard output of the command :\n";
while ((s = stdInput.readLine()) != null) {
stringstdInput += s + "\n";
}
// read any errors from the attempted command
boolean hasStdError = false;
BufferedReader stdError = new BufferedReader(new InputStreamReader(process.getErrorStream()));
String stringstdError = "- Standard error of the command :\n";
while ((s = stdError.readLine()) != null) {
hasStdError = true;
stringstdError += s + "\n";
}
System.out.print(stringstdInput);
if(hasStdError) System.err.print(stringstdError);
} catch (Exception e) {
System.err.println("Erreur: " + e.getMessage());
e.printStackTrace();
}
return exitCode;
}
private static String dpiResolutionToGS(DPIResolution dpiResolution){
String dpiForGS;
switch(dpiResolution){
case DPI72 :
dpiForGS = "screen";
break;
case DPI150 :
dpiForGS = "ebook";
break;
case DPI300 :
dpiForGS = "printer";
break;
case DPI300PLUS :
dpiForGS = "prepress";
break;
default :
dpiForGS = "default";
}
return dpiForGS;
}
Comme vous pouvez le voir, j'utiliser l'ancienne version 9.07 de Script Ghost pour convertir Couleur PDF en PS noir et blanc. Je n'ai pas trouvé une autre solution.