When we have a landscape picture with wide distance range - gradient tool is efficient to create a quality depth map of high quality. Here is an example of making such a depth map in an external graphic editor.

Take the original image.

Figure 6.4  Original image

Create a copy of the original image and open it in external editor with gradient tool support. Then select the area till the horizon line and color it using the gradient tool, as it's shown in the figure 6.5.

Figure 6.5 Use “Gradient” tool

Create a grayscale copy of the original image and invert the colors. (Fig. 6.6).

Figure 6.6 Use “Inversion” tool

Overlay the inverted grayscale image on the gradient image with 50% transparency (Fig. 6.7).

Figure 6.7. Depth map is gotten by means of “Gradient” and ”Inversion” effects union

The generated 3D color anaglyph image is made by using the depth map in the figure 6.8. Use  anaglyph glasses to see 3D.

Figure 6.8. Anaglyph image gotten by means of using the depth map