Every GIMP user might has different techniques to accomplish certain goals. The common technique widely used for colorizing selected area of an image is layer mask. It’s a flexible technique that can be implemented for a wide range of goals. In this article, I am going to demonstrate how to use this technique to colorize selected area of an image, while other areas are made black and white. Following is the final result would be.
Layer mask is a fundamental enough in image manipulation. It allows you to selectively modify the opacity as well as transparency of the layer belong to. Using this concept, you can make certain area of an image remains colorful while the rest is black and white like the picture above.
To create an image like the one above, you will only need a single image, while the number of layer you need is two. Follow the steps below to do so.
Step 1: open the photo
Open an image you want to colorize the selected area of with GIMP.
Step 2: duplicate the layer
You will need to duplicate the layer of the base photo you have just opened at the step above. Simply click the layer icon at the dockable dialogs area (the right panel).
Alternatively, you can click the Layer menu and select Duplicate Layer. To ease your job, you can rename (double-click on the layer name) the new layer jto show that it is a secondary layer.
Step 3: desaturate the new layer
Once you duplicated the new layer, you need to desaturate it. To do so, simply click the Colors menu and select Desaturate.
Step 4: add a layer mask of the secondary layer
The next step, you need to add a layer mask of the secondary layer. To do so, right-click on the layer and select Add Layer Mask. Or, you can also click the Layer menu and select Mask –> Add Layer Mask.
On the appearing dialog, select White (full opacity).
Step 5: select the area
This is the last step, but the most tricky one. This step take much longer than other steps above. Patience is required here. To select the area, you can use the the Paintbrush Tool.
But first, you need to ensure that the foreground color is black.
To save you time and get a better selection, you can use the different combination forms and sizes of the Paintbrush Tool. For instance, you can enlarge the paintbrush on the center area and use the smaller size on the edge of the area you want to colorize. Once again, patience is required here.