It's easy. Copy image location, go under Features/Image Specs Tool, and paste the image location in it. The program will automatically do it for you.
Thank you! Changed in the description. I was too lazy to count manually, because I don't know the automatic way. Therefore, I wrote only the main palette.
Please, check your color count. There are 159 unique colors in your work actually.
Thanks, now busy in creating a prototype game for this mockup. If interested you can follow how it going on my twitter @57wild