Converting PDF pages into images in ASP.NET Core

26 Apr 20244 minutes to read

PdfToImageConverter allows you to convert pages from a PDF document into images using the Convert method. You can convert either a single page or pages into images.

Converting a single page into image

You can export a single page from a PDF file as an image by specifying the page index and setting the parameters keepTransparency and isSkipAnnotations in the Convert method. To preserve transparency in the output image, make sure to set the keepTransparency parameter to true. If you want to exclude annotations and form field elements from the output image, set the isSkipAnnotations parameter to true. Refer to the following code to export a single page of PDF into PNG image.

//Initialize PDF to Image converter.
PdfToImageConverter imageConverter = new PdfToImageConverter();
//Load the PDF document as a stream
FileStream inputStream = new FileStream("Input.pdf", FileMode.Open, FileAccess.ReadWrite);
imageConverter.Load(inputStream);
//Convert PDF to Image.
Stream outputStream = imageConverter.Convert(0, false, false);

Exporting a specific range of pages

You can export a specific range of PDF pages into images by specifying the start and end page indexes and setting the parameters keepTransparency and isSkipAnnotations in the Convert method. To preserve transparency in the output images, make sure to set the keepTransparency parameter to true. If you want to exclude annotations and form field elements from the output images, set the isSkipAnnotations parameter to true. Refer to the following code to export the pages of PDF into PNG images.

//Initialize PDF to Image converter.
PdfToImageConverter imageConverter = new PdfToImageConverter();
//Load the PDF document as a stream
FileStream inputStream = new FileStream("Input.pdf", FileMode.Open, FileAccess.ReadWrite);
imageConverter.Load(inputStream);
//Convert PDF to Image.
Stream[] outputStream = imageConverter.Convert(0, imageConverter.PageCount-1, false, false);

Exporting with a custom image size

You can export PDF pages as images with custom width and height by passing the required size and setting the parameters keepTransparency and isSkipAnnotations in the Convert method. To preserve transparency in the output images, make sure to set the keepTransparency parameter to true. If you want to exclude annotations and form field elements from the output images, set the isSkipAnnotations parameter to true. Refer to the following code to export the pages of PDF into PNG image. Refer to the following code to export the page at the index of 0 into PNG image with the width and the height of 1836 and 2372 in pixels respectively.

//Initialize PDF to Image converter.
PdfToImageConverter imageConverter = new PdfToImageConverter();
//Load the PDF document as a stream
FileStream inputStream = new FileStream("Input.pdf", FileMode.Open, FileAccess.ReadWrite);
imageConverter.Load(inputStream);
//Convert PDF to Image.
Stream outputStream = imageConverter.Convert(0, new SizeF(1836, 2372), false, false, false);

NOTE

To maintain the aspect ratio of output images, you are required to pass the value true for the keepAspectRatio parameter.

Exporting with a custom image resolution

You can export PDF pages as images with specific attributes, such as zoom factor, tile dimensions (x and y), and tile matrix co-ordinates (x and y), by passing the corresponding values as parameters to the Convert method. zoomFactor is used to specify the zoom level. The number of columns and rows will be calculated based on tileXCount and tileYCount (tile dimensions), while tile x and y co-ordinates determine which tile to use based on tileX and tileY. The ScaleFactor property scales the page to enhance image quality, and it can be set to positive floating-point values, with recommended values of 1 or 1.5f. Refer to the following code for exporting PDF pages into PNG images with the desired resolution.

float zoomFactor = 1;
int tileXCount = 2;
int tileYCount = 3;
int tileX = 0;
int tileY = 0;

//Initialize PDF to Image converter.
PdfToImageConverter imageConverter = new PdfToImageConverter();
//ScaleFactor value is set to 1, while the default value is 1.5f.
imageConverter.ScaleFactor = 1;
//Load the PDF document as a stream
FileStream inputStream = new FileStream("Input.pdf", FileMode.Open, FileAccess.ReadWrite);
imageConverter.Load(inputStream);
//Convert PDF to Image.
Stream outputStream = imageConverter.Convert(0, zoomFactor, tileXCount, tileYCount, tileX, tileY);