Hack 68. Change a Scene from Day to Night

Using color-correction tools, you can make a scene that was shot during the day look like it was shot at night.

Not everyone has the experience or luxury to shoot a scene at night. If you find you need a nighttime scene but cannot shoot at night, there are a few color-correction tricks you can use to fake a nighttime look.

Although using color correction to change a scene from day to night is possible, you will get the best results if you can really shoot at night. The real thing is always better.

6.9.1. Using the Color Corrector

The primary difference between a daytime shot and a nighttime shot is the way colors are perceived. You will notice that at night everything takes on a blue-purple hue. This is the effect you are going to mimic.

Color correction deals with color by its very nature. If you plan on playing your movie on a television screen, you should make sure you color-correct using a television for reference [Hack #44]. You should especially be aware that NTSC is sometimes jokingly referred to as "Never The Same Color." This joke is in reference to the fact you can view an image on one television set and then view it on a second and see a completely different image, color-wise.

While using your editing application, locate the scene you would like to alter and select it. Then, open the color correction tool:

Avid

Toolset Color Correction

Final Cut

Effects Video Filters Color Correction 3-way

Movie Maker

Use Pixelan's SpiceFX Pack E1: Correction Effects (http://www.pixelan.com; $14)

Premiere

Window Workspace Color Correction

iMovie

Use GeeThree's Slick Effects: Volume 6 (http://www.geethree.com; $69.95)

There are a few key terms to be familiar with when color correcting:

Chrominance (a.k.a. chroma)

The part of a video signal that includes the hue and saturation

Gamma

The part of the video signal that includes the intensity and affects details

Luminance

The part of a video signal that includes the brightness

In order to create the day-for-night effect, you will need to manipulate the Chroma, Gamma, and Luminance, in addition to altering the blacks, whites, and midtones. Depending on the features of your editing system or the plug-in you have chosen to use, your results will vary. Additionally, every shot is different, due to lighting, the camera lens used, and color composition of the scene, so you will need to adjust accordingly. Figure 6-24 shows the original image next to a day-for-night-effected image.

Figure 6-24. Mele Kalikimaka, during the day and at night

6.9.2. Reducing the Luminance and Chrominance

One of the first steps in creating the day-for-night effect is to reduce the luminance and chrominance of your scene. Obviously, by reducing the luminance, you will lose some of your scene's clarity. But, then again, when you are walking around at night, you can't see as clearly as during the day. Right?

You will also want to reduce the chrominance. This will cause some of the subjects of your scene to not stand out as much. As with all of the changes you are applying, you will need to experiment to see how much chrominance you need to remove. Figure 6-25 shows the image with the luminance and chrominance adjusted.

Figure 6-25. An image with altered luminance and chrominance

6.9.3. Reducing the Gamma

If you have the ability to reduce the gamma of your scene, you should do so. However, keep in mind that a little can go a long way when dealing with gamma settings. Figure 6-26 shows the image with a slightly adjusted gamma level, from 1.0 to 0.95.

Figure 6-26. Slightly adjusting the gamma level

6.9.4. Pushing the Blacks

In order to add a blue-purple hue to your scene, you can push your blacks more toward the blue range of the color spectrum. You do not want to go too far into blue, however, because your image will begin to take on an almost bizarre feel. Figure 6-27 shows the image with the blacks pushed toward blue.

Figure 6-27. Pushing the blacks toward blue, beginning to give a night look

6.9.5. Moving the Midtones

To push the image even more toward the blue-purple hue of night, push the midtones of the image toward blue as well. The initial effect might be a little startling, and your knee-jerk reaction might be to not push too far, so you may have to revisit your midtones a few times as you adjust your image to the desired look. Figure 6-28 shows the image with the midtones pushed toward blue.

Figure 6-28. A sense that it's getting later in the day…

6.9.6. Pushing the Whites

After you've put so much blue into your image, you'll probably be relieved to find out you get to play at the other side of the spectrum. When dealing with the whites, you will want to push them toward yellow. This seems a little strange, but it will bring out some of the whites within all of the blue. Figure 6-29 shows the image with the whites pushed toward the yellow side of the spectrum.

Figure 6-29. Pushing the whites toward the yellow side of the spectrum

6.9.7. Reducing the Saturation

Last, but definitely not least, you will want to reduce the saturation. By doing so, you will bring down the intensity of rest of the colors within the image. It will also bring your image back from the world of the overly colored. Figure 6-30 shows the image with the saturation reduced by over 50%.

Figure 6-30. Altering the color stauration

Color correction is a very powerful method of altering the look of your video. Whether you want to change a shot from day to night, or simply give your video a unique impression all your own, using color correction tools and techniques will give you the ability.