What color is Photograph, Cooper Union Building ?

Source Crayola® CSS3 CSS4
#4d4b45
 
#414a4c
outer space
#2f4f4f
dark slate gray
#2f4f4f
darkslategrey
#2a2925
 
#414a4c
outer space
#2f4f4f
dark slate gray
#2f4f4f
darkslategrey
#72706c
 
#757575
sonic silver
#696969
dim grey
#696969
dimgrey