I took the center photo with my IPhone on Burst Mode using 10 images stacked together of a sago palm looking into the center.
The image on the left is the original photo converted to black and white followed by an added layer set to COLOR blend mode and a gradient applied. COLOR blend mode lays the color on top of your image but not as a solid, so you can see the details through the color.
The image on the right is the original image with an added layer and gradient set to MULTIPLY which darkens the colors.