Possibility to store images as part of data sets

For some types of data, it might be useful to attach images (photos or sketches) to data sets.

Examples:

• photos or sketches of sampling devices as attachment to sampling methods
• photos showing sampling sites to get a more clear impression of the sites characteristics
• pictures of samples to get a visual impression of there properties

Where is this meaningful and how can this be implemented?

How does the file size need to be limited to keep server performance balanced.