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Does Ibex perform internal downsampling of images?

April 26, 2017downsampling ibex images Internal perform

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Does Ibex perform internal downsampling of images?

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PDF internally stores images as JPEG files or bitmaps. If the input file is in JPEG format by default no downsampling is done. If it is in another format such as PNG it is converted to a JPEG to reduce size, at JPEG quality 75%. The PDF generated by Ibex is not specifically optimized for screen or print. Using the dpi attribute you can control the resolution of images on a per-image basis. By default we use the dpi value from the image, so the image is not changed unless the dpi attribute is used (on the fo:external-graphic element, see the Ibex manual). We have customers who generate PDF files at 96dpi for viewing on screen then regenerate them at 1200 or 2400dpi for high quality printing. Of course 2400dpi images result in very large PDF files and display very slowly in Acrobat reader.