For this tutorial the greyscale and image have been sized to 350x350.

Take this image to Image Magick.

Note: For best results, always place the darker

of the two images as your last layer (on top).

Choose the Composite tab.

Enter the Url of this grayscale (#808080).

Now choose "CopyOpacity" from

the Composite dropdown menu.

Click the "Composite" button.

Your result will look like this on the

Image Magick screen.

Now choose the Composite tab again.

Add the Url of this background image.

Choose "DstOver" from the dropdown list.

Click the "Composite" button.

This is the result of the composite.

Then take the image one step further

by going to enhance and click "Normalize"

to correct the gamma and contrast. Click the

Enhance button and this is your finished image.

Note: Depending on the images you are using

you may also need to adjust the Hue slightly.

Output and collect your new image.