You never want to “rescan” or change the resolution (X and Y dot counts) of your image, but you do want to print it the size you want. So you may want to use PhotoShop to change the DPI value stored in the image file from 72 to something higher, up to about 150, or even 300 for very dense photo quality printing.
Puede que quiera usar PhotoShop para cambiar el valor de PPP guardado en el archivo de imagen de 72 a una cifra superior, a 150 o incluso 300 si desea una impresión fotográfica de alta calidad.