tips to enlarge images for offset printing in photoshop

[suzy-q]

I need some tips to enlarge small images so they have enough resolution for offset printing at 150 line screen

[Per Berntsen]

What are the pixel dimensions and intended printed dimensions for a typical image?

[c.pfaffenbichler]

Please show the actual image/s and give a meaningful explanation about the necessary print size. 

GIGO applies as usual, but some Resample Methods may provide more pleasing results (try the Preserve Details-ones) and sometimes adding noise can help »drown out« certain artefacts. 

[marliton]

Hi.

In offset, you need a 1.5 to 2 quality factor. That means, at minimum: 150 * 1.5 = 225 pixels per inch (final resolution).

Try to not use interpolation when you scale images. If is necessary to use interpolation, try "preserve details 2.0".

Maybe these links can be helpful:

https://helpx.adobe.com/photoshop/using/image-size-resolution.html

https://photoshopcafe.com/resize-images-photoshop-keep-quality/