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TGH (short for “Tactile Graphics Helper”) is a free iOS app from The Smith-Kettlewell Eye Research Institute that makes tactile graphics more accessible to people with visual impairments.

The basic idea of TGH is to track the user’s pointing finger as they explore a tactile graphic, announcing text-to-speech information about the location they are pointing to.

To use the app, the iOS device is mounted on a tripod so that the camera captures a clear view of the tactile graphic, and the user tapes a small paper fingertip marker to their pointing finger. When the user points to a tactile feature on the tactile graphic with their finger, the app uses computer vision to recognize the fingertip marker pointing to the feature and issues text-to-speech information about the feature. (For example, for the tactile US map, TGH announces the name of the state that the finger is pointing to.)

TGH is accessible to blind and low vision users and can help them learn “graphicacy” (literacy with tactile graphics); however, please note that in its current (beta) version, TGH requires assistance from a sighted person to aim the camera properly on the tripod before the app is used.

TGH currently supports four commonly used tactile graphics. If you want to try out TGH but don’t yet have any of the supported tactile graphics, you can download a pdf version of any of the supported tactile graphics for free and print it out as a sample tactile graphic. The fingertip marker, which is a small black-and-white barcode pattern, is also free to download.

For information about TGH and TGH resources, including a Tutorial, pdf of the fingertip marker, and the list of supported tactile graphics, please visit: 


Smith-Kettlewell Eye Research Institute
27.2 MB

Requires iOS 10.0 or later. Compatible with iPhone, iPad, and iPod touch.



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  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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