Being able to use stock images effectively is an important part of learning Photoshop. This will guide you through the creation of a piece of virtual graffiti and in the process explore techniques which can be used for editing stock images in other ways. And yes virtual graffiti is legal, begging the question; if more people used Photoshop would there be less kids on the street? FULLVIEW
Begin by creating a new document at 1600x1200px. Now choose the wall you will be vandalising, the one I chose is: Yellow Wall. Paste this image into the document you just created then hide the layer.
Now we need an image to use as a stencil, this can anything but some image will be more effective than others. You can download the image I use here: Jeep. This image was good as the person that had uploaded it had already removed the background. Paste this image into the same document then resize it like shown below.
Next select the jeep layer then image>adjustments>threshold and keep the default settings. Now select>color range and using the eyeper click on any white area in the document OK, next we want to feather this selection so as to smooth it slightly so go select>>feather at 2px OK then hit delete and unhide the wall layer.
Here I added some text in the default Stencil font at 120pt using black. Right click on the text layer then rasterize type. Hit Ctrl+E to merge the text layer and the jeep layer, name this layer 'original'.
Now we will make it look like we sprayed over the stencil, in order to do this, first Ctrl click on the stencil layer to make a selection then select>>expand by 40px then select>>feather by 10px. Create a new layer (Shift+Ctrl+N) then hit Shift+F5 to fill the selection and use black as the colour. Now deselect by clicking Ctrl+D, next Ctrl click on the 'original' layer and feather this selection by 2px, select the layer above it, the one we just created then hit delete and hide the original layer. If you followed these steps correctly the result should look like the image below.
In this step we will create a more spray paint look. Duplicate the top layer and set the blending mode to dissolve, right click this layer then convert to smart object, right click on it again and rasterize layer, set the blend mode back to normal. Now lower the opacity of this layer to 50% and lower the opacity of layer below to 75%, merge these layers by selecting the top layer and hitting Ctrl+E.
We will now try to mimic the effect of the paint running. First create a new layer then select the line tool and by using thicknesses of 4,6 and 8px draw vertical lines by holding Shift like so. The technique being shown here can also be used to simulate a gooey substance dripping from an object.
Change to the brush tool and using sizes 5 and 9px with hardness set at 100% draw dots on the lines to simulate beads of liquid and also draw lets at the bottom of the line.
Change the opacity of this layer to 80% then hit Ctrl+E to merge this layer with the one below.
Go to filter>blur>gaussian blur and use a value of 0.4px.
Using the eraser tool set at size 275 and a hardness of 0% and opacity at 25% start to erase parts of graffiti. This will make it look more worn out. If you have any grunge brushes feel free to use them, for the purpose of this tutorial I decided to use only the default brushes.
Now we want to make the whole image a bit less perfect as in real life things like this tend not to be perfect, such is why computer generated images do not always look realistic. We will use the smudge tool with a size of 85, a hardness of 0% and strength of 50%. Start by smudging the drips horizontally then distort the main image using the same technique. It should now look similar to the image below.
Right click on the top layer, the one with your main image in it and select blending options. Check the gradient overlay and use a gradient similar to the one below, using dark browns and black. Change the gradient type to radial and an opacity of around 50%.
Duplicate this layer then filter>blur>guassian blur with 60px, change the blending mode of this layer to overlay and in the layers panel move this layer down one place. Create a new group and put both these layers inside and change the opacity of the group to 50%.
Now we want the graffiti not to cover the cracks in the wall or the paper on the wall so select the group then in the layers panel click the add layer mask button. Change the foreground color to white. Select the lasso tool and change the feather amount to 2px. Now draw round all the cracks and the paper, don't worry if your mouse is wobbling, it will add to the effect.
After drawing around one element hit delete then Ctrl+D and do this for everything you want your graffiti to be behind. Now change the opacity of this layer to 95%.
Next I added some soft vignetting using a gradient then added a curves adjustment layer with the settings shown below. Note that the red channel is behind the green in this picture.
The technique used next is useful to learn if you want to make the most of layer masks. Download and paste this image into your picture: Texture.
With the texture layer selected, hit D then go select>color range with a value of 200. Click on the groups layer mask then hit Shift+F5 and fill the layer mask with 50% gray. Hide the texture layer and you should be left with the stencilled graffiti.