I always like to see rendered image blended with wireframe view. There may be better samples but here is one: http://www.eddybrown.co.uk/blog/claywireframerender/

First I am getting the wireframe output of my Anadol car model. For the wireframe color, you can change your blender theme, I chose “Pinkified” here.

I moved the lights and background to the second layer. I will just click “OpenGL render active viewport”. Then press F3, you can save the image as a PNG (RGBA) file. RGBA is for transparent image. Don’t worry about the blue background color, it is still transparent.

I also tried to blend “solid” image too, but blending 3 files for one result, it didn’t seem to be proper. So I gave up making the solid output. If you want to render that too, click the same button when viewport is in solid view.

Now for the second last render output, enable all the layers and render. This is our final render that is the same size as the wireframe image.

1-     Use “Adobe Fireworks CS6” (which I like more than the second way)

For image masking there is a nice option at “Commands*Creative* Auto Vector Mask”. Older versions may have “Fade Image” as the same menu.

You need to add your 2 images to your same sized new file. First top layer is our final rendered output, and the second lower layer is wireframe output.

Select the first image and do this easy command:

 

I am choosing “linear” here. So our first layer is masked by a half rectangular.

When you click the right part, you will have control points to slide. If it looks reversed, just click “Reverse Gradients” from the properties.

Then do the same for the wireframe. Edit gradient properties and slide the control points until you feel good.

Here is my blended image. You can save it as JPG now!

2-     To use blender itself

Open a new file, add a plane. I advise you to use “Import Images as Planes” from the add-ons panel. I imported my final render output. And make sure adjust the render dimension as the same as our output images. 

I placed the camera to the top of the plane. Our material is to be “Shadeless”.

In the texture tab, add the other “blendTexture” as a “Ramp” color texture and “wireframeTexture” as file. You can change their names as you understand better. For wireframe image, you may need to check “Premultiply”.

You only need to setup properly “blendTexture”. Check “Ramp” and slide the right color stop towards left. “Ease” option looks better for me.

Press F12 for render, here is my render: