DsPdfViewer allows you to save the modified PDF document as a set of PNG images and downloads the resultant zip archive on the client machine. You can achieve it using the “Save current document as images” button which is placed next to the “Save current document” button on the “Annotation editor” and “Form editor” toolbar. While working on code, you can use SaveAsImages method which accepts name of the output zip archive as parameter and downloads the current PDF document as PNG images in zipped format.

The image below shows “Save current document as images” button in the Annotation and Form editor toolbar:

// Save pages of the current PDF document as PNG images to the specified zip file
viewer.saveAsImages('test.zip');