Sometimes when managing word processing or text documents you might want to save the file in a compressed JPEG format or other similar picture format. I was recently asked how to do this by a Mac user, who was looking for a way to better manage a text document for presenting it in Web pages, but who was also interested in placing a formatted text file as an object in presentations and other Word processing documents.
Not only does converting a text file to an image allow for easier handling when embedding in other documents, but it also allows for easier drawing of annotations and other items on the document when discussing and presenting it.
There are a couple of ways to save documents to an image format. Sometimes programs may specifically support saving to a JPEG, TIFF, or other rasterized format, but since many don't you can take advantage of a couple of technologies built in to OS X that will allow you to do this.
The first is the use of screenshots, which is an excellent way to quickly snap a sample picture of the screen, a window, or a selection of the screen. You can then import the resulting image (by default it's a PNG file) into numerous applications.
While screenshots are useful and convenient, they're limited primarily because the screen resolution on Macs is 72 dots per inch, which means the resulting picture will also be 72 dots per inch. This cuts down on file size, but it also limits the uses of the file to being presented on screen. If you print the file or wish for finer detail of the text by having higher resolution, you can't do this with a direct screenshot. In addition, screenshots are limited to what you see on screen, so if you have a well-formatted document that goes beyond the limits of the screen, then you cannot capture it in an image file using screenshots.
Nevertheless, screenshots have their uses and can be particularly useful for illustrating aspects of what you see on screen. For more details on screenshots see.
Using a PDF intermediary
The next option is a more versatile option for creating a rasterized image of a text document, which is to convert it initially to a PDF and then to one of many image types. In OS X (or in any supported OS that has Adobe PDF installed) this can be done with practically any printable document by printing the file and then using the "PDF" menu in the print dialogue box to either save the PDF or view it directly in Preview.
With the document now open in Preview, you can select "Save As" from the File menu and in the Format window choose one of a number of supported rasterized image formats, including GIF, JPEG, PNG, BMP, and TIFF. Some image formats will have adjustable quality settings, but all should have a resolution option. The default will be 150dpi, but you can increase this to whatever suits your needs. Most printing will not need more than 300dpi, but you can set it to whatever you want.
Keep in mind that the greater the DPI setting the larger the final image will be, especially for nonlossy formats such as BMP and uncompressed TIFF. As an example, saving an 8x11 blank white text document as an uncompressed tiff file at 1500dpi results in a 631.2MB image file. Saving the same document as a JPEG with default quality settings results in a 3.3MB image file.
Once the file is saved you can annotate, crop, and otherwise manage it in ways that would be more difficult if the file were kept as a standard text or word processing file. In the following image example, there is some header information that is placed there by the application being used (in this case I used "TextWrangler"), but this information can usually be removed in the application's preferences.