Today, anyone with a modern smart phone or tablet, can take high-quality JPEG or PNG photos (assuming the light and other factors allow for it). To that end, Adobe introduced Photoshop Touch earlier this year, giving us a true mobile editing platform for our photos.
Currently at version 1.3, Photoshop Touch provides many of the most useful features that the desktop version of Photoshop provides, as part of a touch-based OS, including layers, blend modes and accurate selections. You can even buy a specialized stylus for iPad called the Bamboo, from Wacom, which I recommend.
For this tip we will convert a photo to Black & White, and then add Tint (sometimes called Color Toning as well).
Photoshop Touch allows you to access photos saved in a variety of locations including the built-in Film Roll, your Creative Cloud account and social media. Choose your location (will need to be set up first if your photos are online), and then browse the available shots.
Select the shot by tapping on it and then clicking OK.
Just as we do in Photoshop CS6, it's useful to duplicate the background layer so that you always have your original pixels intact, allowing you to start over quickly. Do this by clicking the button on the bottom right of the Layers panel and choosing Duplicate layer.
At the top of the screen, fourth icon from the right, click the Adjustments option to reveal the different Image Adjustments. These are analogous but simpler versions of the ones found in Photoshop (and a smaller collection overall). Some have settings you can define, others are 'single click adjustments'.
This is one of the 'single tap' options, so no further steps are necessary; just tap the thumbnail to apply the adjustment to your active layer. When you're done, you should see a Black & White rendition of your shot.
Next we need to add some color! Select the Effects settings (top of screen, third icon from right). This will reveal four categories of effects which we can apply, ranging from the more subtle, to the illustrative. Under the Basic category, choose the Tint option by clicking on it.
Three controls will appear: Tint Color, Intensity and Luminosity. Click on the Tint color itself, to reveal the color selection controls. There are three color selection methods you can choose (top-right of the Tint control widget); the top-most option is a color ramp similar to those found in Mac OS apps. From there you can click directly on the color ramp and move your finger or stylus around, and a box with a cross-hair will show the currently selected color.
The last step is to determine once the color tint has been applied, if you prefer to darken the effect (Luminosity) or make the overall effect more subtle (similar to reducing the opacity of the effect, using the Intensity setting). I typically do not darken the image but the Intensity setting is important because it allows you to create more subtle tinting / color toning of the image.
Here's the final image: