Acoustic Picture Transmitter Pro (APT) is a multimedia application available for iPhone users. Developed by Dominik Seibold, this free program allows users to transmit and receive images acoustically.

With APT, users can easily transform each column of a selected image using a Fast Fourier Transform and output it through the iPhone's speaker. On the receiving iOS-device, the received audio is visualized by a spectrogram, making the incoming images visible. This app provides a convenient way to transmit images over a phone or to embed images in any audio recording.

The Pro version of APT offers additional features such as the ability to choose between two coding methods, the option to select between linear and logarithmic frequency scale, and the ability to send the resulting audio as an email. Furthermore, the Pro version is ad-free, providing a seamless user experience.