Example 6: St Vitus's, Prague. Shadow Cast 1

The first place to go to remove blue shadows is the lower left end of the blue curve. To access this, of course, click on the RGB radio button, then drag the lower left corner as shown on the right.

The darker hue clock is much more sensitive to this move, and will move much closer to the middle hue clock, which is our target.

Next, let's add more green to the brightly lit part of the steeple. To do this, drag the upper right corner of the green curve to the left. This time, the brighter hue clock is the most sensitive, and we can drive the hue clocks somewhat closer togehter.

The lighter hue clock also lacked color, so we are glad to see the hue clock hand getting longer, giving us more green to work with.

Now here's the kicker - moving the upper right corner of the red curve vertically downward has a larger effect on the brighter of the three hue clocks. Remember the "string" analogy from last session? As the amount of red changes, think of an arrow between the "r" on the hue clock, pushing the hand away. The other hue clocks are also changed by this by a smaller amount.

One more detail. Let's make sure the sky's color hasn't changed.

No problem - the color has shifted slightly toward cyan, but not enough to worry about.

Remembering the "string" rule, which color, red, green, or blue, do you think would give you the most leverage in moving the hue closer to blue?

Here's the final result. We've matched the colors and achieved the "studio lighting" goal that we are after. It's as if the sky and sun were cooperating, to give us a uniform color.