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## 9.14. Render Pages to PNG

If you want to test formatted text, the only way to do it is to render a PDF page and compare the result with an image of the correctly formatted content. Section 3.20: “Layout - Entire PDF Pages” describes layout-tests using rendered pages. And the utility `RenderPdfToImages` renders a PDF document page by page into PNG files.

### Program Start

    ::
    :: Render PDF into image files. Each page as a file.
    ::

    @echo off
    setlocal
    set CLASSPATH=./lib/bouncycastle-jdk15on-153/*;%CLASSPATH%
    set CLASSPATH=./lib/commons-logging-1.2/*;%CLASSPATH%
    set CLASSPATH=./lib/pdfbox-2.0.0/*;%CLASSPATH%
    set CLASSPATH=./lib/pdfunit-2016.05/*;%CLASSPATH%

    set TOOL=com.pdfunit.tools.RenderPdfToImages
    set OUT_DIR=./tmp
    set IN_FILE=documentUnderTest.pdf
    set PASSWD=

    java  %TOOL%  %IN_FILE%  %OUT_DIR%  %PASSWD%
    endlocal

### Input

The input file `documentUnderTest.pdf` consists of 4 pages with different images and text. The PDF Reader “SumatraPDF” (http://code.google.com/p/sumatrapdf) shows the first page:

### Output

After running the rendering program 4 files are created:

    .\tmp\_rendered_documentUnderTest_page1
    .\tmp\_rendered_documentUnderTest_page2
    .\tmp\_rendered_documentUnderTest_page3
    .\tmp\_rendered_documentUnderTest_page4

The first of these files looks the same as seen with the PDF Reader:

Internally, PDFUnit uses the same algorithm to render the pages as the rendering program does. So, any difference found by a test is due to a change in the PDF document.

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