How can i save a file on localhost on the reduce phase?

[Rodrigo Brito]

Hello everyone. I tryed to process a video using HVPI. It is open source and i founded it on git. I break the video in frames (pictures). So if a try to save these pictures on localhost in the map phase it's work, but if i try to use the same idea in the reduce phase i don't have any errors on my konsole but my file is not save. Is there someone else who understand this behaivior and tell a correct way to do it?

File output = new File("my/path/myfile".png");

       ImageIO.write(value.getBufferedImage(), "png", output);

I just put the code above and this work on map phase and don't work on reduce phase.