Aspect Ratios


You are probably using Cloud Zoom with two images, a small image, and a large image to use for the zoom.

For Cloud Zoom to map from the small image to the large image correctly, both images should be the same aspect ratio. This means that if your small image is twice as tall as it wide, then that should also apply to your zoom image.

If they are not the same aspect ratio, the incorrect part of the image will be displayed when zooming, or you may experience odd stretching/squashing effects to the zoom image.

Examples of correct sizes:

  • Small image = 200 * 300 pixels, large image = 400 * 600 pixels
  • Small image = 150 * 400 pixels, large image = 450 * 1200 pixels 

Examples of wrong sizes:
  • Small image = 200 * 300 pixels, large image = 380 * 600 pixels
  • Small image = 150 * 400 pixels, large image = 450 * 1150 pixels 

Note about iPad/iPhone/iOS


iOS has hard limits built into it regarding the type and size of image that can be used in the browser.

See here:

Here's the relevant extract:

"Because of the memory available on iOS, there are limits on the number of resources it can process:
  • 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."