Choose Do Not Downsample from the sampling pop-up. Some RIPs will still downsample images over a certain threshold, which can be a problem for color or grayscale images that include line art or small text that needs more resolution than the rule-of-thumb 300ppi.
By "sampling pop-up" do you mean the compression tab in the PDF export
options? If so, I've set all those to Do Not Downsample. Attached is an
image showing what is happening. On the right is the original TIF showing
the client the level of pixelation, on the left is the exported PDF zoomed
in to approximately the same scale. There seems to be a certain amount of
anti-aliasing that is happening. Is there a way to turn off any image
processing for linked images? Should the image be a specific type to
Thanks for the quick reply,
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You can't compare Acrobat's and Photoshop's previews to know what's going on with the compression or sampling because they use different view scaling, and what you are seeing might be the previews getting scaled differently to fit the window. Photoshp's 100% view is a 1:1 monitor to image pixel ratio, while by default Acrobat's 100% equals the print output size, so it's difficult to exactly compare pixels.
You have to use Acrobat's Object Inspector to know if there is sampling or compression. So with this Export setting:
I can compare InDesign's Link panel's image info with Acrobat's Object Inspector and see that the image hasn't changed on export. The pixel dimensions and ppi are the same, and Object Inspector's Filters: is blank meaning the image has no compression:
Are you sure you are setting Compression to None as I have in my capture (in addition to Do Not Downsample)? Also, OSX Preview is renown as a bad PDF reader. Acrobat Reader and AcrobatPro also have Preferences>Page Display, which affect the preview. Your 19ppi res is unusually low, so the display pref might be more noticeable.
It looks like the viewer is the issue. I used to hate using Acrobat because it took forever to load and was slow and clunky in its actions. The new version seems to be better. I'll try using that from now on since most people probably use Acrobat reader to view these things anyway. I'll let our team know. Attached is a screen cap of the same file viewed in Preview (left) and Acrobat Pro (right). Thanks for your help. It was driving me nuts. The point of the whole thing is to show the client that 19 ppi is way too low a resolution for a final print. The original was sent scaled down to us but at 150 ppi.