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Editorial Team
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Asked: 2026-06-10T03:21:20+00:00

When viewing images through an iPad (2 and 3) I find that jpeg images

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When viewing images through an iPad (2 and 3) I find that jpeg images are having their dimensions halved in size.

For example an image with the dimesnions 1500 * 1000 will be rendered as 750 * 500. If I copy the image from the iPad and email it to myself then I can see that the dimensions are still 1500 * 1000.

Does anyone know what is causing this and how to stop it from happening?

PNG images with the same dimensions are showing correctly without a problem and I do not think it is anything to do with file size as the some of the jpg images are smaller in size than the png images.

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1 Answer

  1. Editorial Team

    To stop iOS from “downscaling” JPEG images then you need to use progressive JPEG files.

    To create these on the fly (along with optimizing the iamge) you can use JpegTran using the following command:

    jpegtran -copy none -progressive -optimize -outfile output.jpg input.jpg

    I found an interesting article that discusses whether we should be using progressive JPEGs on the iPad and speculates why progressive Jpegs work where others fail:

    http://duncandavidson.com/blog/2012/03/retina_web_thoughts

    Please feel free to contribute or comment on this answer if you have any further information or recommendations on this topic.

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