Вы можете использовать ExecuteGroovyScript
процессор со следующим кодом:
import java.awt.image.BufferedImage
import javax.imageio.ImageIO
def ff = session.get()
if(!ff)return
ff.write{rawIn, rawOut->
BufferedImage img = ImageIO.read(rawIn) //read image from flowfile input stream
def x=100,y=200,endX=800,endY=600
img = img.getSubimage(x, y, endX, endY) //crop
ImageIO.write(img, "png", rawOut) //write transformed image into flowfile as PNG
}
REL_SUCCESS << ff //transfer to success