RGB Gray - Levels Adjustment Layer

Histogram

If we take a look over at our Histogram, we'll a value readout for our image. Basically this Histogram diagram is showing us our Highs, Mid Tones and Lows (shadows/darks) in our image. Shadows are towards the right, Mid tones are in the middle and Highlights (Highs) are towards the right. You can see that in this image there is not a lot of tonal values in our Highs because there is no information located there, and that all are values are pushed towards the left towards our Mid Tones and Shadows.

Add Levels

Levels is an Adjustment Layer and you can find it by navigating to the bottom of the Layers palette and clicking on the half circle looking icon. Click on Levels.

Levels Dialog

Here now the Levels dialog box will appear and give us some options. You may notice that the Input Levels section is basically just our Histogram that we were looking at ealier and we will treat it in the same manner. There are some sliders that we can adjust right below the Histogram and they coincide with the Darks, Mid Tones and Highs because they are color coordinated in Black, Gray and White.

Adjust Sliders

Now the first thing we want to do is adjust the sliders so that we bring them into the first bit of information on our histogram. In this case, we drag the white slider (for the highs) towards the left right until it meets up with the first amount of black information in the histogram.

Finally click OK. You've just now adjusted your exposure for this image.
*End Tutorial*