This attribute is the URL to the main image for your product, which users see first on product detail pages.
The attribute 'image link' is required. Items with no image cannot be submitted. If you want to add more images to your product you can use the attribute additional image link.
Not only your Google Shopping ad, but also your landing page has to contain an image, or at least a placeholder image. Landing pages with no image at all are not allowed.
Sometimes you don’t have appropriate images for each variation of an item. In this case you may submit a single item with multiple values for the variant attributes and use the available image as main image.
Accepted URL protocols for the 'image link' attribute are 'http' and 'https'. In addition you have to ensure that symbols used within the image URL are encoded (e.g. question mark = %3F). Valid file formats are non-animated GIFs, JPEGs, PNGs, BMPs and TIFFs. With regard to the size you have to make sure that the image has more than 100 x 100 pixels (250 x 250 pixels for apparel products), but cannot be larger than 64 megapixels and 4MB respectively. It is recommended to submit the largest, highest resolution, full-size image with at least 800 pixels in height and width.
Google recommends that the product itself should take 75% to 90% of the full image on a solid white, gray or light colored background. The image should show your product with the color, pattern and material that match the title and description. Otherwise your product might be declined.
There is quite a lot restriction concerning the content of Google Shopping images. In addition to the rules you have to take care of for every product, you are not allowed to use placeholder and incorrect product images as well as ones that include borders or promotional elements. Promotional elements could be calls to action such as 'buy', price information, or promotional adjectives like 'best' or service-related information (e.g. free shipping). Furthermore you have to make sure, that the product on the image is not overlaid by obstructing content like watermarks or logos.
Except for products in the categories 'Hardware' and 'Vehicles and parts' graphics and/or illustrations of the products are not allowed. Single color images are just permitted in the categories 'Vehicle Paint', 'Craft Paint, Ink & Glaze' and 'Painting Consumables'.
If your are selling a bundle your image has to show the entire bundle to be approved. However, images of multipacks are valid, even if they display only a single unit of the product. Furthermore be aware of the correctly usage of bundle and multipack.