"harsh contrasts" is a correct and usable phrase in written English.
You can use it when referring to two or more markedly different or extreme things. For example, "The harsh contrasts between the city's wealthy and impoverished neighborhoods are stark and heartbreaking."
(Whistler's immature painting in the Peacock Room retains harsh contrasts of light and dark, unsuited to his talent, from those precedents).
Rwanda is a country of harsh contrasts — of horrifying history and friendly people who welcome you to their homes with a treasured glass of milk.
With uncomfortably intense closeups, disorienting angles, harsh contrasts, and abrupt editing, along with dream imagery and fantasy sequences, he evokes his prime subject: the inner life, and, above all, his own turbulent visions.
The economics of cocoa -- a $5 billion trade that winds from African ports through Dutch and American processing plants to store shelves and children's goody bags -- recall other harsh contrasts in industries like diamonds, textiles and sporting goods, where the glitter of wealth is produced through the sweat of penury.
Dose-limiting transient visual disturbance at 4900 mg m−2 included glittering of objects, harsh contrasts, jerky motion and strobe effects.
The purple and yellow are "not a harsh contrast as we think of now," she said.
It is brusque, almost harsh, contrasting strongly with the elegance of French and English work.
Another criticism I've seen is the harsh contrast between "the fine-grain mono background and harsh 'paint' foreground".
It offers the visitor a harsh contrast to the breathtaking beauty of the country beyond its limits.
The sharp angles and harsh contrast between the black ink and yellowed paper tell us this is a linocut.
