Changing images or image colours in a PDF with Javascript

Hi.

I have a big document with confidential information. We have to send it to a person, but we must to hide some information in it.

My collegue has been working in the document for several days adding white blocks wherever a critic information is. She added a white gif image and rearranged the size for every situation.

Now we have realized that the block should be black.

I tried to run a Javascript to change the colour of the blocks but i't doesn't work.

This is the code:

      // Get a color convert action

       var toBlack= this.getColorConvertAction();

       // Set up the action for a conversion to Black

       toBlack.matchAttributesAll = toBlack.constants.objectFlags.ObjImage

       toBlack.convertProfile = "Apple RGB";

       toBlack.convertIntent = toBlack.constants.renderingIntents.Document;

       toBlack.embed = true;

       toBlack.preserveBlack = true;

       toBlack.colorantName = "Black";

       toBlack.isProcessColor = true;

       toBlack.useBlackPointCompensation = true;

       toBlack.action = toBlack.constants.actions.Convert;

       // Convert the first page of the document

       var result = this.colorConvertPage(0,[toBlack],[]);

Any clue why it's not working or an alternative?