Monochrome on GIMP – using layers
Layers. Everyone knows that the good photo editing software suites have them, but nobody in the world has ever figured out what they’re for.
I’m exaggerating of course, but layers really are a bit of a dark art. I’ve been digging through my photography magazines and how-tos, and here’s a small tutorial on how to use layers to convert a photo to black and white. I’ll be using GIMP, a free and powerful image editing software. Photoshop is similar, just probably a bit better.
This is the photo I chose, a detail shot from the Monument to Discoveries, in Lisbon. Not bad, but not interesting either. However, the texture and shadow-light contrast made me think this would work in monochrome.
First, open the image on GIMP. Drag the windows and toolboxes around until you’re comfortable. This is how I like it:
Here’s a good way to perform the basic mono conversion. Click Colors -> Components -> Channel Mixer. Tick the monochrome box, and move the sliders of the three output channels, according to what color you want to filter for. In this case, I went for 100 Blue, 15 Green. Choose what looks better to you.
The basic conversion lacks contrast. This is normal, converted images usually do look rather flat. At this point I would usually adjust curves, but there are problems with it, which I have documented before. Solution? Try out GIMP’s layers.
To add a layer, right click over the image -> Layer -> Duplicate Layer.
At this point you have two identical images, one over the other; visually, nothing has changed. What we’re going to do now is change the type of light in the second image, the “top” layer. On the top of the “Brushes” palette (the movable toolbox to the right), locate the “Mode” drop list and select “Soft light”. Try other “modes” – you’ll learn something from seeing what happens.
And here is the result. Better, isn’t it?
However, I found the contrast way too harsh. Solution? Reduce the opacity on the horizontal slider under “mode”.