<p>So your filters in the first layer are of size w x h x 3 (for VGG, w=h=3), I'd suggest taking the mean over the last dimension and using them as w x h x 1. As you've probably figured out, you won't need to change any other weights.</p>

<p>This is inspired from a similar approach people have applied to initializing the VGG Imagenet model on flow images.</p>

<p><a href="https://arxiv.org/pdf/1507.02159v1.pdf" rel="nofollow">https://arxiv.org/pdf/1507.02159v1.pdf</a> (Secion 2.2)</p>
how to fine-tune VGG model with single channel input?
<p>The VGG model accept a 3-channel RGB image as input, but my data are single gray images, any suggestions for how to utilize the weights in first conv layer of VGG model?</p>