[ Moved your discussion here for a better response ]
I wasn't aware of the subforum, thanks
- to scale image (not to resize) is possible in InDesign;
- output resolution is an option of export format you will choose;
so do you really want to involve a Photoshop?
I know about scaling and output resolution, my problem is that I often get similar images in different sizes. One might be integrated in the layout at 100% of its actual size, the other one at 30%. So when I want to sharpen them, in order to keep it consistent, I have to resize the files to their size in the layout at equal resolutions.
Here's the script we use for resizing images. (Note: it has "resize only the selected image" option). However, it doesn't sharp images in Photoshop (you can record this step with script listener and add it to the script). If an image is placed more than once, the largest instance is set to 100%, the other instances are scaled proportionally by InDesign so visually it looks exactly the same after resizing.