How to Raise an Effective PPI in InDesignby Jennifer Hearing
InDesign seems to offer unlimited design and production potential. But transferring designs into printed material may raise unforeseen problems. Most printers require the industry resolution standard of 300 ppi. PPI stands for "pixels per inch" and affects the print size and quality of your images. But if you do not have images saved at the correct ppi, or if you don't have the time and resources to resize all your images, you can raise the ppi using InDesign without opening each image in Photoshop.
Create a new document in Photoshop. In the New Document dialog box, create the new file with these settings: make the resolution 300, select "CMYK Color" for the color mode, change the "Background Contents" to white, and make the width and height match the size of your InDesign document.
Save and name the Photoshop file as a JPEG. Choose the "File" menu and "Save," or the "File" menu and "Save As."
Open your InDesign file and create a new layer on your master page. For this process, all your images should be on one layer and your text on a layer above the image layer.
Move the new layer you created (for new Photoshop file) above the images layer, but below the text layer.
Import the Photoshop file you created and be sure it is located on the new layer and on the master page. Make sure the placed JPEG covers the entire page.
Select the JPEG frame with the direct selection tool and change the blending mode to "Multiply" in the effects panel.
Export your InDesign file as a PDF. Choose a method that incorporates "transparency flattener." The most commonly requested preset with this setting is "PDF-X/1a:2001." The transparency flattening process chooses the top image (the transparent Photoshop 300 ppi file you created and placed on the master page) when it merges the layers together.
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