Impressive boar, but those pics have made the rounds before. Doesn't even need to be photoshopped. Pretty simple perspective. Notice something funny about the pose? Most hunters and others who want their pictures with a trophy want to be touching it, or holding the head up, sitting on it, etc..... No such in these pics. So they are behind the boar a bit. Notice that the men in the group photo are blurry - DOF problems because the photo is a closeup of the boars head throwing the men out of focus. Also notice in the single shot that the camera is well above the boar, but all you see of the man who is behind the boar is his head, and notice in the group shot, and in some other shots from the site - the knees are well below where the head is resting. The boar is on a high spot, while the men are lower. Rather simple with a wide angle - exaggerates the size and makes it appear the men are near the boar because they are still in somewhat focus. Ya wanna know how to make a fish look big - hold it up close to a wide angle lens.
Although a boar that size is possible. - There have been ones killed in the 1000 lb range. World's largest pig was a domestic from Jackson, TN in the 30's that tipped the scale at over 2200 or 2500 pounds - I cannot remember which. There was also a domestic one of about 1600 pounds somewhere in the Midwest I believe.
I believe there is only one group certifying record boars, and their record is just a hair over 700 lbs. A big hog killed in Alabama tagged Hogzilla was probably bigger in the 800's but was buried before weighing. Later the boar was exhumed and the biologists estimated it to be 800+ not the 1200 lbs the shooter claimed, also about 4 foot shorter than he claimed also.