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Any downloaded resource, whether it’s HTML, CSS, JavaScript, images, or non-streamed media, must be less than 10 MB. The 10-MB limit applies to the encoded size of images. There is also a limit to the decoded size of images. See “Optimize Images.”

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The maximum decoded image size for GIF, PNG, and TIFF images is 2 megapixels. That is, ensure that width * height ≤ 2 * 1024x1024. The decoded size of animated GIF images must be less than 2 MB. For large animated GIFs, only the first frame is shown.

The maximum decoded image sizes for JPG images is 32 megapixels (due to subsampling), which allows JPG images to decode to a size that has 16 times fewer pixels. JPG images larger than 2 megapixels are subsampled — that is, decoded to a reduced size. JPG subsampling allows users to view images from the latest digital cameras.