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