Which word is the antonym of ‘luminous’?

Read the poem given below and answer the following question.

I was four in this photograph fishing                                                      

with my grandparents at a lake in Michigan.                                                       

My brother squats in poison ivy.                                              

His Davy Crockett cap                                                 

sits squared on his head so the raccoon tail                                                        

flounces down the back of his sailor suit.                                             

                                                           

My grandfather sits to the far right                                                        

in a folding chair,                                                          

and I know his left hand is on                                                   

the tobacco in his pants pocket                                               

because I used to wrap it for him                                                           

every Christmas. Grandmother's hips                                                    

bulge from the brush, she's leaning                                                        

into the ice chest, sun through the trees                                               

printing her dress with soft                                                       

luminous paws.                                              

                                                           

I am staring jealously at my brother;                                                     

the day before he rode his first horse, alone.                                                     

I was strapped in a basket                                                         

behind my grandfather.                                              

He smelled of lemons. He's died--                                                          

but I remember his hands.