1. A digital X-ray imaging system comprising: X-ray generator means including an X-ray tube; X-ray generator controlling means for controlling said X-ray generator means; X-ray detecting means for detecting an X-ray transmitted through a subject, said X-ray detecting means having an X-ray grid for shielding a scattered X-ray; signal processing means for acquiring signals from said X-ray detecting means and processing the signals to obtain a digital X-ray images of said X-ray transmitted subject through said subject; display means for displaying an image of said subject obtained by said signal processing means; position changing means for changing a relative position between said X-ray detecting means, said subject and said X-ray tube by moving one of said X-ray detecting means and said X-ray tube; position change controlling means for controlling said position changing means; and imaging-sequence controlling means for controlling said position change controlling means and said X-ray generator controlling means; wherein said imaging-sequence controlling means controls to set a plurality of imaging view fields, to set each of a plurality of regions of interest of said subject to generally a central area of an X-ray detecting plane of said X-ray generating means, said X-ray detecting plane being an incident plane of said transmitted X-ray through said subject, and to set at least one imaging view field to contain an intermediate region between said plurality of regions of interest, and said signal processing means corrects a sensitivity non-uniformity, caused by said X-ray generator means and said X-ray detecting means, of each of said digital X-ray images of said plurality of imaging view fields, and joins together a plurality of said digital X-ray images of said plurality of imaging view fields.