To find text or images and replace it in a PDF.

$doc = new PDFDoc($filename);
$replacer = new ContentReplacer();
$page = $doc->GetPage(1);

// replace an image on the page
$target_region = $page->GetMediaBox();
$img = Image::Create($doc->GetSDFDoc(), $imagename);
$replacer->AddImage($target_region, $img->GetSDFObj());

// replace a text placeholder
$replacer->AddString("NAME", "John Smith");

// replace text in a given region
$text = "hello world";
$replacer->AddText($target_region, "hello world");
$replacer->Process($page);

Replace PDF text or images
Full code sample which shows how to use pdftron.PDF.ContentReplacer to search and replace text strings and images in existing PDF (e.g. business cards and other PDF templates).