Will Google follow link if anchor tag content is blocked?

Question

This is a followup on a question I was asking here: Cropping images & SEO

Basically, if I have something like this:

    <a href="<Full_Res_Image>"><img src="<Cropped_Image>"></a>

and Cropped_Image is blocked by robots.txt,

1. Will Google still crawl to Full_Res_Image and index that in its web search as well as Google Images?
2. If it does crawl to the full res image, how do I then set alt tags on the full res image?

If these are not feasible, then do you have any pointers on how to show cropped images for user/page-load friendliness, while still having Google Images index the full res image and not the cropped image?

P.S. The reason I want to set alt tags in (2) is for SEO for the images.

Answer 1

Will google still crawl to Full_Res_Image and index that in web as well as google images?

Yes.

If it does crawl to the full res image, how do I then set alt tags on the full res image?

You can't but you can still use other indicators of content such as:

1. Use the alt attribute on the cropped image. By being the effective anchor text of that link it would be logical to assume it would confer meaning to the linked full res image.

2. Use the title attribute on the anchor tag.

3. Use metadata in your images.