Creating black-and-white photos is without doubt one of the most important techniques of image processing. Black-and-white images are perfect for emphasizing shapes, light patterns, and composition while removing the distraction of color. This is why even today most art photography is published in black and white.
In this post I will show you a case study of creating a black-and-white photograph using Snapseed, my favorite photo-editing app for both the iPhone and iPad. I will use the following image as an example.
This photo was taken yesterday near the Museum of Amsterdam. It currently does not look particularly spectacular, but the light patterns on the floor and on the columns as well as the background textures on the left suggest that it might look better in B&W. The faces of people (click on the image to see a larger version) also add to the story of this photo.
We start by launching Snapseed, tapping Open and selecting our image from the Photo Library. If you want to follow along, feel free to download the above image to your iPhone. Next we want to find Black & White on the menu to the left.
After tapping on Black & White select the effects menu which is denoted by a star and two horizontal sliders (see below). Here you can select multiple pre-configured B&W image settings to see some examples of what you can possibly do. In this case I selected Neutral and manually adjusted contrast and brightness afterwards.
First I adjusted the contrast of the image. In this image (and in many others) I preferred to increase the contrast a little. This makes the image look more dramatic and highlights the light patterns I mentioned earlier. To adjust contrast, simply swipe on the image vertically and a new menu will pop up as seen below. Here you can select which adjustments you want to make.
To change contrast, simply swipe horizontally until you find a value that looks best. In this case I settled for +25, which helps me emphasize the light patterns but still preserves most details in the shadows. Feel free to experiment with a wide range of values to see what works best in each case.
The image above is rather dark. In particular, the shadows on the right are nearly black after I increased contrast. To correct for that, I also increased the brightness of the image.
In this case I increased brightness to +20. Note how the people on the right side are now more prominent in the image. Quite often I increase both contrast and brightness of the same B&W image. That way I can emphasize interesting light patterns without making the shadows completely black.
At this point we are almost done. In fact, if we saved the image now, it would already look great. However, before I finish I want to add just a little vignetting to gently emphasize the central parts of the image.
Before we can add any additional effects to the photo, we must process what we have so far. Simply tap the little triangle on the bottom-right corner and your current effects will be processed and saved inside Snapseed (but not to camera roll).
After the image has been processed choose Center Focus from the effects menu. The following screen will appear.
Note that by default Blur has a non-zero value meaning that the non-central parts of the picture will become blury. In this image I wanted no additional blur, so I changed Blur to zero. Next I tapped on the effects menu (the one with a star) and chose Vignette.
Within Vignette I selected Outer Brightness by swiping vertically (see below). This allows me to decrease the brightness of just the outer parts of the image to add some vignetting.
The key to doing vignetting is to not overdo it (as seen above with outer brightness set to -95). Vignetting is a great way to draw the eye to particular parts of the image, but it works best when it is subtle. If vignetting is too obvious, all the magic is gone and you are left with an image that is simply black in the corners. In this case I settled for -60.
Finally, in Snapseed it is possible to adjust both the size and position of the center of vignetting (or any other center-focus effects). Center size can be changed by pinching two fingers, and the position can be adjusted by dragging around the blue dot in the center of the circle. Note how I adjusted the center so that it exactly contains all the important parts of the image (including people).
Now that we are finally done with editing this image, we can tap the bottom-right triangle to process it. This, however, will not save the image to camera roll, so we also want to make sure we do that. After processing, simply tap on the share button in the top-right corner and choose Save to Photo Library.
This is the final result of this editing (click to enlarge). It surely looks better than the original.