For my latest class project, I took a walk around my neighborhood and captured images of interesting vignettes. I then pulled out four Pantone spot colors from each of my three favorite images, using Photoshop's eyedropper to identify the RBG color and then using Pantone's website to select the closest Pantone color:

I picked the birdhouse image for further color exploration.

For the first variation of the birdhouse photo, I converted the photo to tritone, using the red, green, and blue Pantone colors. Then, I adjusted the curves for each color. I added more red to the highlights and removed some blue from the highlights to give the image a slightly pink tone. (Without that, it was hard to tell that there was any red in the image at all.) Then, I tinkered with the blue and green curves to lighten up the image a bit...I added some blue to the shadows and reduced green in the midtones. I like how the total effect is an image that's a little warmer than a basic grayscale image, and that it calls more attention to the mottling on the tree bark.

For the next version of the birdhouse photo, I used spot color channels for all four Pantone colors. I posterized the image into four levels, then applied blue to the white level, green to the light gray level, red to the dark gray level, and gray to the black level. (Then I had to copy the spot channels over to layers so I could generate an RGB jpg for this post. You're welcome. ;) ) The spot color channel technique resulted in an image in which red is a much more prominent color than it is in the other two variations. It feels like that gives this image a sinister, horror movie kind of feel.

For the third variation, I applied a 4-stop gradient map, running gray, red, green, and blue from left to right. To prevent the image from being too dark, the gray, red, and green are grouped together in the left half of the gradient. The result is similar to the spot-channel image but with less red. The result reminds me of a photo negative...although the tones aren't inverted the way a negative would be (i.e., the shadows in the image in the photo are still dark, the highlights still light), it has a similar surrealistic feel.

I was surprised to realize that the spot color channel variation is my favorite. I think this is because that variation represents the biggest departure from the original image, in terms of both appearance and feel.