You can do it using Media Gallery (it exists for articles, products, collections and pages content block). Go to "Blog Posts" section menu.
Follow next steps:
- Select blog from the tabs list.
- Choose the article which you need.
- At the content editor menu find "Insert Image" button.
- In the opened media uploader select exist image or upload new with "Upload" button at the bottom.
- Press "Insert Image" button.
- Click primary "Save" button.
For each language you can create unique content with completely different images ( watch the video ).