Your screen has a lot lower resolution than what you print
Screen, 72 dpi (dots per inch) vs. offset printing, usually 300 dpi minimum.
A 21" diagonal screen displays the same amount of picture as a 5" diagonal printed piece.
Simply "blowing up" a low resolution screen image to paper gives very poor images.
If you know the number of pixels high and wide an image is. divide each by 300. Print it as that many inches. or less.
Beware almost vertical or almost horizontal lines these can produce a jagged "step" effect. Create a higher resolution image if you can.
The resolution of vector graphics (Illustrator & Corel) is not a problem because they are redrawn with full detail each time they are scaled and rendered.
Images shrink from screen to paper. Small text or intricate images will print with a quarter as high as on the screen. Will yours still be legible?