So first, what i'd do is,
- Make a selection of the vehicle and Copy the selection onto a new layer (Ctrl+J)
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- Then introduce your Rust/Dirt texture images and place them over your Car Cut-out.. Create a Clipping Mask between your Texture Layers and the Cut-out of your car. Do this by Right Clicking on your Texture Layer and selecting the "Create Clipping Mask" option. Alternatively, you can Press down your Alt Key and Click on the line dividing the two layers.
If your Texture Layers are in the PNG format, that's great. You already have a transparent background. So all you have to do now is Transform the layer to match the perspective of the car.
- Select the Layer and press (Ctrl+T) to Free Transform. To change the angle and change the perspective, hold your Ctrl Key and click and drag the corners of the Free Transform Grid.
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Move it around to cover the areas that you want it to cover and hit Enter. You can Erase the texture off from the areas that you don't want it to cover later on.
- But now, if your texture files are in the JPG Format, they're going to have a solid background, and it will look like this,
[ATTACH=full]83835[/ATTACH]
- In that case, to get the background off, you're going to have to use Layer Blending Modes. Blending modes are found here.
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- Now, since our Rust Layer has a White background and the Rust is darker than the white background, we will have to use a blending mode that affects the white (lighter) background while leaving the rust (darker) as it is. The Blending Options that I would use is "Darken" - Darken affects the light parts, leaving the Dark parts unaffected. Opposite to this is the "Lighten" blending mode; it leaves affects the Dark parts, leaving the Light parts unaffected.
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You can choose between Darken, Multiply, Color Burn, Linear Burn and Darker Color; they all come under one category.
- Lastly, if you want the rust to go along the contour of the car, I'd use the Warp Tool. To use to Warp tool, Select your layer, Ctrl+T, Right click on the Transform Grid and select Warp.
[ATTACH=full]83838[/ATTACH]
And you can repeat the same steps for the other layers as well.
With better quality images, more precision and trying out different methods, you could get the perfect results. Hope this helped you.
