For thousands of years the basic workflow involved in making realistic pictures of things has, at its core, stayed the same.
The first step is to have illuminated subject matter.
Light from this subject matter is focussed as a real optical image onto a megapixel sensor.
The megapixel sensor transduces the image into data that travels as electrical pulses up a cable.
The cable feeds the electrical pulses into a memory where they are temporarily stored.
The picture memory is sent to a processor where it may be edited, perhaps stitched with other picture files, and given the HDR treatment.
The resulting picture file is prepared for output via some sort of mark-making device which either places spots of paint or ink on a surface or glowing dots on a monitor screen.
This array of points forms the picture.
People familiar with digital picture-making will instantly recognise the separate roles of camera, computer, and printer/monitor in the short narrative above.
People familiar with painting and drawing will find the same narrative just as familiar. The lens and megapixel sensor are of course the artist's eye, the retina is the light sensitive transducer, the optic nerve is the cable and the signals it carries are the data. In addition the memory and processor are parts of a brain, and the mark-making device is usually the artist's arm, hand, and brush.
Digital picture making is a remarkable technical achievement in that it mechanizes and automates the traditional work flow conducted by painters and draftsmen over the centuries. The insight that digital picture makers haven't grasped is that they are fully legitimate participants in the grand artistic tradition that includes Leonardo da Vinci, Michelangelo, Vincent van Gogh, and hundreds of other super-stars of Western art! The other heavy implication is that if we accept a "photograph is a picture that results from the capture of an image using light projected through an optical system onto a megapixel sensor" then that perfectly describes the Mona Lisa. Leonardo's famous portrait would qualify as a photograph! And indeed, by carrying the argument forward, we end up with: all pictures are photographs!
In a world where photographs are what megapixel sensors make it is hard to see what qualities a picture would have to have in order not to be a photograph. There is a logical and conceptual failure in the "megapixel sensors make photographs" premise and we should put it aside.
And then separate to all of the above there is picture-making that is unarguably photography. I mean the art practiced by Louis Daguerre, Edward Weston, Ansel Adams, Diane Arbus, and millions of others great and not so great. Here again is the same illuminated subject matter, a lens, an image, and a sensor but that's where things get very different. The sensor absorbs a physical sample of the subject, suffers chemical changes that become marks, and the array of marks constitutes the picture itself. There is no transducer, no data, no memory file, no processor, and no mark-making device that fabricates pictures by emptying the memory of someone or something.
Digital picture-making mimics painting and drawing. Photography does not. They are radically different enterprises that become muddled with one another because the pictures they make can, on the surface, look similar. Some pictures are photographs and some are not. Both forms are fully capable of containing high art. I think the distinction between the two systems will always be crystal clear to serious inquiry that digs beyond the superficial.