<p>Yes, this is possible, but not with standard CNN architectures, some changes are needed:</p>

<ul>
<li>One approach is CNNs with binary weights, so evaluating the CNN can just be done with bit operations. There are many publications about this, like <a href="https://arxiv.org/abs/1602.02830" rel="noreferrer">this</a>, <a href="https://arxiv.org/abs/1603.05279" rel="noreferrer">this</a> or <a href="https://arxiv.org/abs/1511.00363" rel="noreferrer">this</a>. I have seen an implementation of YOLO  with binary weights running in real-time on an iPhone, so it is definitely possible.</li>
<li>A second approach is to reduce the number of parameters of the neural network, for example if you train a network with 5000 weights and gets detection performance that is close to what you want, then this network might run in real-time. But this is harder.</li>
<li>Third approach is just to optimize the neural network architecture to minimize parameters, and combine it with a very optimized implementation. There are algorithms to speedup convolution operations, such as <a href="https://arxiv.org/abs/1611.06473" rel="noreferrer">L-CNN</a>, or the ones implemented by cuDNN.</li>
</ul>

<p>A very good related resource are the presentation and papers from the <a href="http://allenai.org/plato/emdnn/index.html" rel="noreferrer">The 1st International Workshop on Efficient Methods for Deep Neural Networks</a>.</p>
Deep learning for face detection in mobile device
<p>I want to create a face detection mobile app and I want to do it with a regular Deep Learning(Convolutional Network). I will train it with my computer and use trained data in the mobile app.</p>

<p>My question is that: can I get very fast computation in the regulat phone like iPhone? I need it be very fast and under 1 sec can detect a face in the video. Is it possible on a mobile device? or this kind of task need more powerful hardware?</p>

<p>I know training phase must be in a powerful computer but I mean production phase in a mobile device. </p>

<p>for example, if I put my phone in a street, It can detect all peoples face with the same deep network in training phase?</p>