Photoshop Tutorial: Adding Grass to an Image

This tutorial was prepared in Adobe Photoshop CS3. Yes, I am that far behind.

I live in West Texas where good grass is a rare thing. Most yards are balding brown, some even downright dirt. It’s no surprise to me when someone asks me to add grass to an outdoor shot they need.

I’ve never written a tutorial, but I thought I would give it a try. For those of you who have a newer version of Photoshop, I’m sure the concept is the same though the tools may be different. Also, I’m sure there is an easier way to do this, probably much easier than I did it. If you know of a way, tell me about in the comments below.

I was given several pictures of the same general area that needed to have grass added. I did the same to all, but I’ll stick with this one for the tutorial:

Original Un-edited Dirt Shot

The first thing I noticed was that this was apparently shot with a wide angle lens. Any grass I add will need to reflect that same stretched, graduated look. I also see that there’s some extraneous stuff that can be trimmed, such as the dirt on the sidewalk at the bottom and the bit to the left of the lamp post. Trim away.

The next step, at least for me, was identifying a good clip of replacement grass. All I needed to do was search “grass” under Google images. I was presented with much more than I could have ever looked at in one setting. Give it a try and see what comes up.

I needed a wide angle shot that included some depth of field without losing focus. Anything with sky was out. I also needed it shot from the correct angle, 20-30 degrees down. That eliminated a lot. I also needed something that would fit the area, which meant fescue. Lastly, it needed to be pretty big so that I would not have to worry about enlarging it (which never turns out good for resolution). This is a reduced version of what I ended up using:

Grass image used for replacement

Now that I had my replacement grass, it was time to get rid of the dirt… which is something my wife says pretty often. I grabbed my trusty Polygonal Lasso tool and went to work outlining the areas of dirt that I wanted to replace. I zoomed in quite a bit so I would get an accurate placement for my selection, but you don’t need to be too precise. For something of this nature, close is fine. In defining the selection, I made sure not to make the lines too straight and regular. We’re talking grass here, and no grass is straight. Especially the grass the runs along the edge of the sidewalk. Once I had my three areas of dirt selected, I simply deleted the selections. That left me with something like this:

Image with dirt selections deleted

Notice I said “something like this.” If you look closely, you’ll see weeds and sprigs of grass sprouting up along the edges of the sidewalk. I did not create those with the polygonal lasso tool. These were added in the next step with my eraser tool and the grass texture. There are a large number of unique textures available in Photoshop and you can chose several different types to add irregularity to the edges of your deleted selection. When we actually add the grass in, this will give it a more realistic look.

The next step is to add the grass into layers underneath your deleted sections. This is where your eye for perspective must go to work. Simply dropping in the image of grass behind it will not work. Notice in the original grass image, grass in the foreground is larger than the back. There is already a sense of perspective to our grass image. To make this work, you’ll have to stretch and distort the grass image. It will take a bit of massaging and playing, but eventually it will click into place. I did the same for every area of dirt in my image, manipulating the same grass image (or a portion of it) three times until it felt like the grass blades were the right size and the perspective fit.

Grass Inserted in layers beneath original image

Now we have beautiful grass that needs a bit of edging from the local landscape guy. That’s his problem, not mine. What is my problem, though, is the unnatural brightness of the grass. This is a sunset shot and the grass has the appearance of mid-day. This is easily solved by dialing it down a bit. You’ll have to play a bit to get the right look. In this shot, the grass in the foreground required me to turn the saturation down 40 points and the lightness down 20 points. Both these can be found under the Hue/Saturation settings. The grass on the far left is exposed to the setting sun, so I didn’t turn the lightness down quite as much. The grass on the far right is already in shade, so the lightness went down a bit more.

To finish it off, I selected the original layer and juiced up the saturation just a hair to add more colors. Here’s the final image:

Final edited shot with grass

So… what do you think? Is there a better way? Something easier that I missed? Sound off and let me know.