According to the classic composition rules of landscape photography, the sky occupies three-fifths of the height above a real or imagined horizon. This creates a significant light intensity between the lower and upper parts of the image, which then comes back into balance: thus, they put an end to the blurred sky and underexposed landscape. The blue gradient filters from COKIN enhance the blue color of the sky and emphasize the colors of mountainous landscapes. They are also ideal for seascapes, as they highlight the white of the crashing waves.