Thanks Eugene but this method will not provide the control I need to spit the png's out with a given file name nor the option to export at various sizes (72dpi, 144dpi etc).
Ideally there should be an option to create a library of assets then export them out as individual images…
Sorry - all there are are workarounds! Illustrator is great for this type of work - but not InDesign! Maybe some day they'll give us an Asset Export tool!
For now - try File>export and choos Epub.
For image format choose the PNG format and your resolution.
Once the Epub is written you can then change the extension to .zip and unpack the files.
You might need iZip for the Mac if you can't unzip it directly.
But once again the images are arbitarily named.
Basically - how does InDesign know how to name them? It would need to pull the image file name and use that - plus the resolution and size would be helpful.
I think perhaps a script could do it you should ask on the- InDesign Scripting
Here's a workflow that comes close, perhaps. But, there is no ability to apply a filename to the exported assets now have them auto update when changed.
You know if you export the INDD file as HTML (File > Export > HTML), there is a doc-wide Export Options panel that will allow you to specify the resolution of image exports. You get a folder called "[doc name] Resources" after the export, and inside there you'll find an Images subfolder with auto-named images. However this only applies to actual images in the layout. It sounds like a) you want to specify different resolutions to different image exports, and b) have ID export a selection (multiple objects) as a single image. Yes? You can do that.
1. In InDesign, select the object that you want to export as an image -- either a placed image that you want exported at a custom res, or a grouped selection of whatever that ID will rasterize on export -- and choose Object > Object Export Options.
2. Click the EPUB and HTML panel and choose "Rasterize Container" from the Preserve Appearance from Layout menu.
3. Fill in the fields for image Format, Resolution, Quality, etc.
Grouped objects that you've set ID to rasterize on export are still editable in the layout. It's only when you export to HTML or EPUB that they get rasterized as a single image.
I don't think the Articles panel will help at all here. It's mainly for changing the linear order of objects in an exported EPUB, if you choose Article Order in the EPUB Export dialog box. HTML exports ignore the Articles panel.
Does that help at all?