PDFBox offer functions to render a entire page, but no way to render only a specific rectangle of the page.
It seems the only way to achieve that would be to use PDFRenderer.renderPageToGraphics and configure the Graphics2D object so only the region of interest is rendered, but I can't figure out how to do that.
Another way would be to render the whole page, then extract a sub-image, but I would like to avoid this.