Today’s Question: Suppose I’m creating a fairly large print such as 20×30 and want to do a test print but not waste a full sheet of paper that large size. How can I isolate a portion of the full 20×30 and print on smaller paper to evaluate what that section of the 20×30 would look like when printed?
Tim’s Quick Answer: My recommendation is to prepare the image for the full intended output size in Adobe Photoshop, and then drag that image into a new document sized to the paper size you want to use for the test print.
More Detail: It can actually be a little bit tricky to create a print that represents a portion of a larger print, with that portion being printed at the same size as it would appear in the full print. You need to be careful not to resize the image (or portion of the image) to a different size.
One of the easiest approaches to this task in my view involves Adobe Photoshop. Start by preparing the image for the final output, such as by creating a copy of the image, flattening the image, resizing to the intended print size (including the desired pixel-per-inch resolution), and applying sharpening for the final print. This image will be the basis of a final print at the full size, but of course as long as you keep this image open you can always go back in history to refine the sharpening. You could also use a Smart Filter for this purpose.
Next, create a new document by choosing File > New from the menu. Change the unit of measure for Width and Height to the preferred setting (such as Inches) using the popup to the right of each of those fields. Set the Resolution value to the same setting used when preparing the full-sized image for print. Then set the Width and Height values based on the size of the portion of the image you want to print for your test print. This could be, for example, the dimensions of the paper size you’ll use for the test print. Keep in mind, of course, that the printable area may prevent the image from actually printing to the edge of the paper, depending on your configuration.
You can then drag the full-size image into the test print document. You can view the images side-by-side by choosing Window > Arrange > Tile All Vertically from the menu. Then select the tab for the full-size image, and drag the thumbnail for the image on the Layers panel into the actual document area for the new document you created. You can then select the Move tool from the top of the toolbar (or by pressing “V” on the keyboard) and drag the full-size image around within the new document you created, to determine which portion of the image will actually be printed.
You can then print the new document to test the results for a portion of the image printed at full scale in terms of how it will appear in the final print. You can of course make changes to the source image as needed before committing to a complete print of the full-sized image.