How to Change Image Dimensions in Indesign?

Oh ok! I think I see what you mean now I thought there was some way you can change the dimensions manually, guess not. Thanks you for you inputs! I'll gladly use them.

When you are designing for web or screen you can easily set the export pixel dimensions of a page or image by using pixel ruler units for the page dimensions.

So here my page dimensions are 2000px x 1500px, and the image on the page is 1000px x 650px. If I export either as a JPEG or PNG at 72ppi, the exported pixel dimensions will be the same.

The page exported to JPEG at 72ppi:

When you export as JPEG choose Maximum quality, 300 ppi. Unfortunately there is no option for setting the dimensions of it. It's all done by math 😉 

Instead, if you need to export a JPEG to a specific file dimension, like 1000 pixels wide, use the free script from Keith Gilbert. It's explained in this post and you can download from there too: https://indesignsecrets.com/new-indesign-script-to-export-jpegs-at-a-precise-size.php

AM

Try 150PPI in the Export JPEG dialogue box.

What resolution are they in the Export JPEG dialogue box?

I'm not clear why you are creating Posters and Banners in InDesign and then exporting them as JPGs?

Have you exported them as PDFs?

Perhaps Packaging the InDesign files  might be the best method of storage.