Click here to get PANORAMA.JPG with all the images for use in this tutorial.

Select the Color Selection tool and, on the floating Tool Properties tab, set the Tolerance to 50. Click in an area of blue sky.

You'll note that not all areas of sky have been selected - the Color Selection tool with a tolerance of 50 (range is 0-255) will select an area containing a range of colors either side in hue from the one you clicked over.

Hold down the Shift key on your keyboard and click in the unselected areas above the horizon (mainly clouds). Each click will increase the area selected. You should be able to select all areas above the horizon with about 10 additional clicks. The selected area should look like image A.

Select the Curves dialog from the Image/Adjust menu. 

The graph depicts the spread of lightness values for all pixels in the image, from shadows up to highlights. Before you make any changes, each portion of the curve has an equal input and output value, hence you see a straight line. By dragging points on the line, you can lighten or darken pixels in any portion of the spread.

Click in the middle of the line (the mid-tone region) and position the mouse over the node that has appeared. Drag the middle of the line down and to the right slightly so that it looks like image B. Dropping the curve depresses the output values (especially in the mid-tones), for a darkening effect.

Choose the Red channel from the list at the upper left. Now instead of affecting all color channels equally, your adjustments will affect only the Red component of pixel values. Adjust the curve so that it looks like image C. You should adjust the green and blue curves, and for full-size versions based on the examples below. Click OK when you are happy with your changes.

We're about to cut out an area of our selection to change its shape. Select the Rectangular Selection tool. Hold down the Alt key on your keyboard and draw a rectangular marquee from the small, dark boulder at the top-right of the bush in the foreground to the upper right corner of the image. Release the mouse and Alt key. Your selection should now just occupy the top-left of the image above the mountain.

This shaped selection will allow us to modify just this part of the image. In the case of the Lens Flare we're about to add, it will mean that it's only visible above the rocky horizon.

Choose the Render/Lens Flare menu item from the Image menu. Add a Normal lens flare, with Intensity 125, to the jutting peak of the mountain. Click OK.

Draw another rectangular selection marquee, the full height of the image from a point to the left of the foreground bush to the right-hand extremity of the image, as indicated in image D. Add another Lens Flare, with the same position and settings. Because of the new selection in place, this will only paint the lens effects in the foreground.