The first time Photo Lab is opened, it is shown in Simple mode. This means that there are some Photograph Setup presets to the left, and some Post Processing presets to the right. The idea is that you should be able to create a nice, high quality rendering simply by selecting a preset. Note that Post Processing effects only can be applied to rendered images, i.e. photos with a green frame.

At the top of the Post Processing area are three buttons for auto-adjusting the photo. You can either make the photo brighter, darker, or auto adjust it in terms of exposure, brightness, contrast, saturation, temperature, and tint. Click Neutral to return to the original settings.

The post processing presets available are Neutral, Vignette, Old Photo, Cartoon, and Pencil Sketch.

From the Simple mode, you can switch to the Advanced mode where you can control each setting down to the last detail. 

Neutral

Resets photo to it's original settings. No post processing effect is added. Use this if you are unsatisfied with other effects you have applied and wish to return to the original photo.

Vignette

Draws interest to the center of the photo by fading to black at the edges.

Old Photo

Adds the vignette effect and desaturates colors, almost giving a black-and-white effect.

Cartoon

Adds more pressure and definition to the contours around the objects and increases saturation of colors.

Pencil Sketch

Generates a hand-drawn, sketchy impression in black and white, with heavier, wavy contours around the objects.