How to get the image to be continuous with the 3D surface.
Imagine you have an image like this:
And what you want to do is have the black parts as positive relief on the surface of a cylinder. Note also that the background is not entirely white, it is light gray.
When you bring in the image to PhotoToMesh you'll need increase the contrast and brightness a tad to get the background to be white. You do this in the image import wizard:
Simply setting contrast and brightness to 2 the background changes from light gray to white.
Now, since we want the dark parts to be high in the relief we need to check Invert Mesh as shown in step 1) below:
If we left it at that we would get the black parts being raised, but the white parts, the surrounding rectangle, would be lowered into the body of the cylinder:
The "background" is the object's surface everywhere except where your image is. Luckily you can tell PhotoToMesh to assume that outside of the photo area the background should be considered white. That is step 3 in the vignette dialog as shown here:
And the result is shown here:
By putting Background Greyscale to 100% we are saying "all areas outside the image are to be considered white" which means that the white of the image, around the dark pattern, blends in smoothly.
This technique works for V3 and V4 of PhotoToMesh.