Photoshop - Adjust Contrast Using Levels

Here are two images,
The first doesn't have enough contrast and the second has too much contrast.

We can adjust this using the Levels tool in Photoshop.

Open the first image in Photoshop.

Go to Image > Adjustments > Levels

We are going to set the parameters for how bright and dark we want the brightest and darkest parts of our image to be.

 In the Levels pop-up, double click on the white eyedropper which is the one to the right.

 In the box which pops up, enter the value 245 for each of RG and B.

We are telling photoshop that we don't want white to be totally white when our image prints.

Click OK

 In the Levels pop-up, double click on the black eyedropper which is the one to the left.

In the box which pops up, enter the value 10 for each of RG and B.

We are telling Photoshop that we don'y want the black part of our image to completely black, we want to see some detail.
Click OK.

Click OK in the Levels pop-up window and when asked if you want to save these changes, say Yes.



Now at the bottom of the Layers panel, click add a New Adjustment Layer (it looks like a half moon) and choose Threshold.

The Threshold dialogue box will pop up.

Drag the handle in the Threshold window all the way to the right.

 Your desktop will now be showing you the brightest parts of the image.

Select the eyedropper tool and hold it over one these white areas.

Hold down the Shift Key and Left Click.

You will see that a little number one has been placed to mark this bright spot.

Now move the handle in the Threshold pop-up all the way to the left. If the image is all white, move the handle gradually to the right until some black begins to appear.

Now select the eyedropper again. Hold it over one of the black areas, press the Shift Key and Left Click.

This area has been marked with a number 2.

Now that we have these markers we can delete the Threshold Layer.

Right Click in the layer and click Delete layer

Now back at the bottom of the Layers Window, click Add New Adjustment Layer again and select Levels.

In the Levels dialogue box which pops up, select the white eyedropper and click in the Number 1 target in your photo to adjust the highlights of the image.

Now select the black eyedropper and click in the Number 2 target to adjust the shadow in your image.

You should see that your image now has much more contrast.

You can adjust the mid-tones of your image by moving the central handle in the levels pop-up. 

To delete the number targets from your image, select the Colour Sampler tool from the Tool Bar and in the control panel click clear.

These handles won't appear in your printed image if you don't delete them.