Does Mobile Safari have an image file size limit?
This official article what you are looking for. As expected there is no file size limit, the answer is more complex and depends on the device memory and image compression algorithm used:


  
  The maximum size for decoded GIF, PNG, and TIFF images is 3 megapixels
  for devices with less than 256 MB RAM and 5 megapixels for devices
  with greater or equal than 256 MB RAM. That is, ensure that width *
  height ≤ 3 * 1024 * 1024 for devices with less than 256 MB RAM. Note
  that the decoded size is far larger than the encoded size of an image.
  The maximum decoded image size for JPEG is 32 megapixels using
  subsampling. JPEG images can be up to 32 megapixels due to
  subsampling, which allows JPEG images to decode to a size that has one
  sixteenth the number of pixels. JPEG images larger than 2 megapixels
  are subsampled—that is, decoded to a reduced size. JPEG subsampling
  allows the user to view images from the latest digital cameras.
  The maximum size for a canvas element is 3 megapixels for devices with
  less than 256 MB RAM and 5 megapixels for devices with greater or
  equal than 256 MB RAM.