In TYPO3 6.1, how to configure CSC content fallback only for images

Question

In a dual-language (single-tree) TYPO3 6.1, I have a completely regular texpic content element.

TSConfig: mod.web_layout.defLangBinding = 1

TypoScript:

config.sys_language_overlay =1

temp.lead < styles.content.get
temp.lead.select.where = colPos = 2

How can I tell css_styled_content to use the image from the main language if no other image is specified?

Setting config.sys_language_mode = content_fallback won't help, as we only want images to fall back, no Text.

The original image is appearing in the localised record, but greyed out:

Answer 1

There is a slightly hidden button to the right of that entry that editors can use to localise that file reference:

Once localised, the reference works as expected.