The way that you are loading your image is one of the best ways to get an image ranked in Google image search. See this answer of mine. So even if you are using some PageRank, it is hardly being wasted, it is being used to rank the image well in Google image search.
However, it is impossible to waste link juice within your own site. About 10 years ago, Google changed the way that it handles internal links and PageRank. Internal link "PageRank sculpting" will no longer affect rankings.
I'm not sure exactly how it works internally in the Google algorithms, but from a webmaster perspective you can do linking that you might think would hurt your SEO:
- You can link to pages you don't expect to rank.
- You can link to things in robots.txt.
- You can use nofollow on internal links.
I tend to think that Google is using some sort of domain authority. I divides your domain authority up among all the pages it wants to index (probably proportionally to PageRank). If Google doesn't want to index a page, it ignores it and doesn't allocate any of the domain authority to that page. This allows the indexed pages on your site to get all the domain authority, even if you have lots of links that "waste" PageRank.
Bottom line: don't worry about links to large images in
noscript. They won't hurt your site at all and they are helping your images rank in image search.