Try scaling up the image that you want to import before you import it then scale it back down again by the same ratio in the image import tool. If you import a bigger image and then scale it down in the import tool you should get a better quality image.

i've tryed that with the maximum jpeg possible but still i can't really get the quality i want. since is a ensemble of elements, maybe is worth the try to import image element by element in order to scale up a little part at the time. isn't this making the final project very heavy or not? about the dxf? any idea how i can scale it down? or has to do with the other reasons?

@ginopaolo It is recommended to import images under the following formats : JPG / PNG / GIF / BMP / SVG I advice you import your image under PNG format and as @andyfierman says, try to import a large scale image to save the image details and then scale it back to the desired size. Chech this link it may help you about the DXF format import : [https://docs.easyeda.com/en/Import/Import-DXF/index.html](https://docs.easyeda.com/en/Import/Import-DXF/index.html)