You don’t say what you have tried or search for. We are here to help, but asking folks to do your work for you is why consultants exist. 8^}
So, you have a CSV Base64Image data strings, not real pictures, meaning created using other tool?
ADDS will only take pictures of a given size, and this is documented in the MS TechNet/MSDN documentation and many blogs all over the web.
So, you need to know the file size of each image (recommended thumbnail photo size is 96x96 pixels and maximum size of photo that can be imported with the Import-RecipientDataProperty command is 10-KB), and if it does not meet the ADDS specifications, you need to fix that.
There are many examples and even pre-built script showing how to import images in to ADDS, for example:
There are many similar locations taking to converting image to base64, and we can only image some of there tools were used or done say this way…
# Convert image to base64
$b64 = [convert]::ToBase64String((Get-Content 'F:\Pictures\SecureZip.jpg' -encoding byte))
All that being said, converting and resizing on the fly, that is a different process
Converting, base64 string back to a file, say, using something like...
FromBase64String() method converts a base64-encoded string to a byte array. All you need to do is write that byte array back to a file:
# Path to new image file
$filename = 'D:\temp\imagefile.jpg'
# Convert base64 image back to image file
$bytes = [Convert]::FromBase64String("$b64")
Then resizing that image using say this: