Is this possible please.
each product will be available in up to 16 different colors.
choose products on desired color from home page menu.
the main product image is automaticly changed to show the disired image and not the other 15 images in each product
I am sorry if i have not described this very well.
What is your Magento version? If you have Magento 1.9.1 or later you can use Configurable Swatches and make your image change when needed combination is selected from drop-down.
If you older version, this functionality is not included out-of-the-box and can be achieved using extensions.
If you are using Magento prior to 1.9, you can try this extension https://amasty.com/color-swatches-pro.html
Here are some of its features: