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Help: Scanning a document

Note: Scanning in PDFpen requires a scanner supported by the Image Capture application.

The usefulness and ease of working with scanned content depends a lot on the quality of the scan, and also on the bulk of the scanned material in terms of document size. The larger the document, the more unwieldy and longer it takes to process. Keeping scans small enough to meet all your needs is key to document performance. Some setting recommendations are highlighted below.

Scanning from PDFpen

Choose File > Import from Scanner. You'll see the following Scan window interface:

scan bed

Kinds of Scan

The kind of scan chosen has the biggest impact on file size and what is stored:

  • Text:
    Black and white, 1-bit, smallest file size, good for text documents. A single letter-size page at a resolution of 300dpi (dots per inch) will be anything from 75k to 200k in size.

  • Grayscale:
    Choose 256 gray levels or thousands. 256 gray levels should be more than adequate in most cases. Good for text documents with photos or diagrams that are not color. Generally this scanning mode is either 8 or 16 times larger than Text, so expect a single page at 300dpi to be 1MB-2MB in size.

  • Color:
    Choose millions or billions of colors. Millions of colors will yield approx 4MB per page at 300dpi, billions considerably more.

Note: Moving from Text to Grayscale can sometimes allow you to drop the resolution and still yield excellent quality. Something you might scan at 300dpi as Text may come out fine at 200dpi in Grayscale, or in color. Levels of gray or colors often make up for loss in resolution. Experimentation can help to achieve trade-offs of resolution and grayscale or color against file size.

Another setting that effects the file stored is the Format setting. This lets you set the image encoding stored in your document. Generally TIFF will be the largest and will not compress well for grayscale or color. TIFF is desirable for when Text is the kind chosen. JPEG is the setting you should use for compressing photographs. Otherwise, the general setting for most purposes is PDF.

Settings listed in the Scan window below the Format menu are scanner-specific.

Scan Preview

A preview of the page in the selected scanner is automatically created when you open the Scan window. PDFpen automatically sets the size and position of the page based on that preview. You may prefer to adjust it to letter or A4 size. Letter is 8.5 x 11 inches (215.9 x 279.4 mm), and A4 is 210 × 297mm (8.27 x 11.69 inches). If you do adjust the size, you'll also want to drag the outline area to fit the entire page.


Once you're done with your settings click "Scan" to scan your document. Once scanned, a new document will open containing the scanned page. To continue scanning, change the page in the scanner, and click "Scan" once again. This new scan will be added to your document. Press Cancel or close the Scan window when you have finished.

The "Detect Separate Items" box can be used to scan each outlined part of the preview page separately. In general use you will leave this box unchecked, but it may be helpful to separate unrelated content on a page.

Adjust, Resample, Deskew

To compress a scanned document, see Saving and Compressing File Size.

If you want to alter, enhance, or otherwise adjust a scanned image or document, look under the Edit menu to find these options:

  • Adjust Image… For images, not for pages or documents. It opens the Image Edit panel which enables you to adjust the color (exposure, contrast, saturation, etc.) of the image as well as apply effects. Go to Edit > Adjust Image…
  • Resample Image… Reduce a file‘s size by changing the resolution and reducing the depth of color. Select a specific dpi or switch the color to grayscale or simpler. Go to Edit > Resample…
  • Deskew and Adjust Image… Make fine adjustments to the “skew,” or tilt, of the image, page, or document selected, as well as adjust contrast and exposure by choosing Edit > Deskew and Adjust Image…

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