I know, that looks simple, but there is some level of difficulty to this. I have to take an image and somehow separate the part I want to leave colored from the parts that I don’t. For this one, I made a copy of the image first. Then, I removed all the color by changing the image to gray scale. Then I changed it back to RGB color. Trying to cut all the little details and protrusions off at one go was impossible, so I did it in parts, on the copy of the original image. I actually ended up cutting the little crosses and details off last, zooming in very close to the image, and cutting around individual pixels in some places. I did have to go back and clean up the final version a little, getting rid of blue sky that had transferred with my little cut-and pastes. Staying zoomed in, I just used the eyedropper to pick up the gray sky color, and then used the pen tool to get rid of the little bits of blue.
It took me about half an hour to do that image, for those of you who care.