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I create a Layer with a text field that has a display pattern for calculated values. The display pattern code checks if the Content Item has a file extension that is a variation of .jpeg and horizontal and vertical resolution are 72DPI. Both of these values are read out of your image on ingestion into the Content Platform. This is a highly configurable .liquid template so you can of course add in as many criteria as is required for your business case. 
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Example .liquid display pattern for calculated values
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