You can now publish a VM Image in Shared Image Gallery (SIG) to Azure Marketplace. This capability simplifies your image preparation, testing, and submission process as you no longer have to extract vhds, upload them, and generate SAS URIs. With this capability, you can now manage the full image lifecycle within Azure. You can simply create your image from the VM or a vhd into Shared Image Gallery,then select the SIG Image to publish it in Partner Center.
Learn more about publishing your VM image using Shared Image Gallery here.