Just adjusting the hue isn’t enough to make an object look metallic. Here, you’ll learn how to adjust the colors in a realistic way and add a metallic shine.
This technique works best on things that are mostly a single color – photos of human hands, plants, and some animals work well. A zebra would give poor results.
Open a new file in Photoshop with your starting image. For this example, I’m starting with a photo of basil.
Add a gradient map layer via Layers–>New Adjustment Layer–> Gradient Map:
Change the blend mode of the Gradient Map layer to color.
Pick a metallic gradient. Changing the color to make the object look copper or gold helps sell the illusion, but isn’t necessary. To help show that the metallic look isn’t just about the color change, I’ve chosen a steel gradient.
Steel and silver aren’t just black and white. If you look at an actual photograph of either metal, you’ll see hints of color where light or shadows reflect. Even this subtle color helps sell the illusion we’re trying to create.
I don’t like any of the default metal gradients, so I’ve made several of my own using colors sampled from photographs of different metals. You can download them here.
Now I’ve got a picture of basil that’s almost black and white, and doesn’t look at all metallic. To make it look shiny, first add a Curves adjustment layer via Layers–> New Adjustment Layer–> Curves. The Curves layer should go above the photo and below the Gradient Map layer
Next, adjust the curves profile. To make the object look shiny, add several peaks and valleys. In general, the spikier your curves profiles is, the more places you’ll see light “reflected” off of your object. Here’s the curves profile I’m using:
And now you’re done! Here’s my final metallic basil:
You can make this look like different kinds of metal by changing the gradient on the Gradient Map layer. I made copper and gold basil.
And a few other metal things: