Hi here is my code in Producto.php, is a little change from the "extend a basic site" tutorial. (staff part)

class Producto extends Page {
   static $db = array(
   );
   static $has_one = array(
   'Foto' => 'ProductPage_Image'
   );

   function getCMSFields() {
      $fields = parent::getCMSFields();

      $fields->addFieldToTab("Root.Content.Images", new ImageField('Foto'));
      return $fields;
   }
}

class Producto_Controller extends Page_Controller {

}

class ProductPage_Image extends Image {
   function generateThumbnail(GD $gd, $width, $heigth) {
      $gd->setQuality(90);
      return $gd->paddedResize($width,$heigth,"F0F0F0");
   }
   
   public function Thumbnail($width)
   {
      return $this->getFormattedImage('Thumbnail',$width, 70);
   }
}

i create a few page of this type and add images to every product.
All this works perfect in live site, Thumbnail are created perfect.

But in CMS when click "Files & Images" i get : Fatal error: Class 'ProductPage_Image' not found in D:\...\sapphire\core\model\DataObject.php on line 1096

Why i get this error?

The class ProductPage_Image *must* be in a file called ProductPage.php

If you want to put it into Producto.php, you should rename the class to Prodocto_Image. If you do this, remember to run db/build, and then edit the current images in the database, changing the File.ClassName field.

Works Perfect Thanks.