Pinch to Zoom. Would it be necessary to label or indicate interaction with image

Question

I have an app that allows for pinch to zoom in mobile version. This is a nice feature.

• Do you believe it is good practice to label or put instructions on the image to indicate it can be zoomed on by pinching?

or

• Does this clutter the display and over explain a well accepted practice that most user intuitively use?

Answer 1

What about a small onboarding?
I think in this case it's not that disruptive and makes sure that all your users understand their possibilities, instead of just the more "techy" ones, who are already used to modern interaction styles.

When the user opens this section with the image for the first time, you can show an overlay that briefly explains the interaction.

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And after the first use never show it again.
Optionally, you can add a checkbox saying:

To give the user more control.

Answer 2

As pinch to zoom is a standard gesture on all the major mobile operating system (Android, iOS, and even the lesser-used ones), there should be no need to label it.

It depends on the context, though -- it needs to be clear that something is zoomable. For example, I would expect a map to be zoomable, but not a simple list of text elements. If it's not clear that something is zoomable (you can do some quick user tests to find that out), consider adding some cues that it is.

Answer 3

When om mobile, I do expect to be able to zoom into everything on a web page, not just images. In fact, I get really upset when site owners restrict the ability to zoom on mobile sites.

What you can do is to let the user to tap on the image to shot it on a modal. Then, the user can pinch to zoom the image. When the user taps outside of the modal, that modal is closed. But don't forget to provide a close-button on the top right of that image/modal.

Bottom line: There is no need to be able to label your images.