Is there a way to select every other page in a pdf and convert it to grayscale?

Question

I'm going to ask this question in a few sub-forums, so if you think you've seen it, you might have. Someone suggested it might be done with Javascript. I know nothing about Javascript.
Where I work I use a program that can print to pdf. We use it to produce mailings, usually postcards, that are addressed.
I often end up with a 500 page document that will print on 250 sheets of cover stock, which will get cut into 1,000 postcard, all pre-addressed and sorted by zip code.
Usually, the address side is all black and the front is color. The printers we use can print a black click on the address side and a color click on the other, IF the pdf is set up that way. Otherwise, both sides will be counted as color clicks.
I know I can select pages individually in a pdf and convert them to grayscale and those pages will be counted by the printer as black clicks, which are cheaper than color clicks.
The problem is, I have not figured out how to convert all the odd numbered pages to grayscale at once. As a result, I usually end up printing the color side simplex, then putting the job back in the tray and printing the black side. Of course, that only works if only one side is personalized, sometimes both sides are.
Is there a way to select every other page in a pdf and convert it to grayscale?

Answer 1

The Acrobat SDK has sample code that shows how to convert the colors for one page (the first page of a document). This sample can easily be adjusted to process every other page. You can then use an Action that executes this JavaScript to process the document. Do you know how to create an Action? If so, you can use this script (as I said, adapted from the sample in the SDK) to convert all odd pages (1, 3, 5, ...):
// Get a color convert action
var toGray = this.getColorConvertAction();
// Set up the action for a conversion to RGB
toGray.matchAttributesAny = -1;
toGray.matchSpaceTypeAny = ~toGray.constants.spaceFlags.AlternateSpace;
toGray.matchIntent = toGray.constants.renderingIntents.Any;
toGray.convertProfile = "Gray Gamma 1.8";
toGray.convertIntent = toGray.constants.renderingIntents.Document;
toGray.embed = true;
toGray.preserveBlack = false;
toGray.useBlackPointCompensation = true;
toGray.action = toGray.constants.actions.Convert;
// Convert every other page
for (var i=0; i<this.numPages; i++) {
  console.println("Processing page " + i);
  if (i % 2 == 0) {  // change to "if (i % 2 != 0) {" for all even numbers
  console.println("in page " + i);
  console.println(this.colorConvertPage(i, [toGray], []));
As I've indicated in the code, you can change this to all even numbers by changing the == to !=