It's a good idea to avoid extreme scaling both in expanding and reduction. And you may have to stay around 85/115% ratios.
But the best thing shouldn't be to let the pictures 100% scale ?
Yes but, your document is now compler, all your pictures placed and the last thing you want is spend time modifying all the pictures one by one. So who cares after all, I make my PDF, and let the publisher deals with that. If you do so, it's probably meaning you like playing to the russian roulette (can I just say that ?).
Consciously letting important scales values in Indesign, You are giving to the PDF Engine the control over your image resampling and it's like asking the baker to lay your carpet. And Photoshop does that so well...
Ok but It's not tellin me how to resize all my images in one step! Just use this script from Kasyan Servetsky that will ease your life !
Open a document and run the script.
Resizes all raster images in the current InDesign document and sets them to 100%.
Currently supported image formats: TIF, PSD and JPEG. Supported interface languages: English (default), Russian and French.
Bitmap images are not resized.
All modified links will be automatically updated and all missing links will be ignored.
The script allows selecting a list of 'ignored folders' – that is the images in these folders will not be resized.
If one or more images are selected in the current document, 'Resize only selected images' checkbox becomes enabled – if you check it, only selected images will be resized.
All settings you choose in the dialog box are remembered, even if you quit InDesign. You have options to resize anchored images, images located on master pages, pasteboard.
You have also an opportunity to pre-check for missing links: if such a link is found, the script will show it.
The script can create a report on the desktop, containing detailed information about resized images; if such a file already exists, the information appended to it.
Another option is to check effective resolution of all images: if you select it, the script will find all images with effective resolution below a certain level – 300 dpi by default – and will give you a warning about them.
If you placed the same image more than once, the largest instance will be resized in Photoshop and all other instances will be resized in InDesign accordingly.
For enlarged images, you have the option:
- Resize without resampling
- Resize with resampling