InDesign image quality is terrible, what could be the problem?

Question

Layouts and prototypes

The quality of png images (icons - size 240x240px) is terrible when exporting a document to pdf from InDesign (see screenshot), although it displays perfectly in InDesign. When pasting, I reduce the pictures (50x50px) in compliance with the proportions (but even without resizing everything is terrible).

I looked through the manuals, went over articles and questions on the Internet, tried everything indicated - it didn’t help, I did:
1) inserted not only by dragging, but also File -> Place ...
2) converted to jpg format with background filling
3) I have the property pictures on Display Performance -> High Quality Display
4) changed the settings for Export... to high
PS: if you missed something in the manuals, please poke your nose. I would be grateful if there is a way out without redrawing the icons in illustrator.

Answer 1

It doesn't matter how you save the image to disk. When you add it to pdf, all pictures are re-encoded in jpg with the parameters that are set in the pdf editor. So check the jpg compression settings in the pdf editor and the dpi value in it. Also, try to use the "for printing" profile when generating pdf (just so that larger dpi are used).

Answer 2

It is best, of course, to vectorize your icons, then there will be no questions about blurring.
To minimize the loss of image quality, I think Photoshop will help. Make their size such that they stand in the layout without scaling - 100 percent. Leave the resolution at 300 points. When exporting to PDF, disable resampling completely - set the output, compressions parameters to none.