Blurring a picture

One of the main limits of the Poser material room is the lack of direct picture manipulation nodes, such as a 'blur' function. As so often, there is a way around this (actually there are several ways round this - more of the others at a later date).

Here I am going to look at two ways of using the U_Offset and V_Offset channels on the Image_Map node. These allow you to move a texture around in the final render, displacing it around the UV map of its surface. If we combine those channels with a random number, then we will get a simple blur.

Fig 1: Unblurred Image

Figure 1 shows our initial image - a simple image node plugged into the diffuse channel of a sphere. The picture is entirely unblurred.

Fig 2: Simple Blur

Figure 2 shows a simple blur. Here, the image node has been altered to produce a very fuzzy result.

Fig 3: Shader Tree for Simple Blur

We have achieved this by plugging a noise node into the U_Offset and V_Offset channels of the Image Map. U_Offset and V_Offset have been set to 0.05. The higher the number we use here, the more blurred the result will be. The noise node randomises that offset, so that each pixel in the final picture is taken from a different random direction.

Fig 4: Complex Blur

This is ok if we want a very fuzzy blur, but often we want to see a bit more of the original picture, with blurred edges (see figure 4). We can do this, but it will take a couple more nodes.

Fig 5: Shader Tree for Complex Blur

To create our more complex blur we add two more elements to the shader tree. Our aim is to merge a blurred and unblurred picture. The final result shows the original picture with a blurry 'halo' caused by the noise node. In order to achieve this, first we need to adjust our simple blur slightly. In our original version, the blurring pushes our picture up and to the right, as the blur is always added to the original position. Now we want our blur to be centred around the original picture, so we have altered the min to -0.5 and the max to 0.5. The result can be seen in figure 5, where in the final result the telegraph post (top centre of the picture), is surrounded by the blurred picture.

The second change is that we have added another copy of the main picture, then used a blender node to merge the two pictures. Increase the Blending value to increase the influence of the blurred picture, decrease it to reduce the blurring.

In both of these examples, you might need to adjust the scale of the blur depending on the size of the final render. The larger the blurred picture will appear in the final image, the smaller U and V offsets will be needed to achieve the same results.

Suggested Variants

Try replacing the noise node with a 3D Wave to get a very different result.