Apple Color 1.5 - Manual (Page 28)

• 10-bit images, on the other hand, use a full range of 0 to 1023 to store each color
channel. (Again, Y
′
C
B
C
R
video uses a narrower range of 64–940 to accommodate
super-black and super-white.) The additional numeric range allows for smoother
gradients and virtually eliminates bit depth–related artifacts.
Fortunately, while you can’t always control the bit depth of your source media, you can
control the bit depth at which you work in Color independently. This means that even if
the source media is at a lower bit depth, you can work at a higher bit depth to make sure
that the quality of your corrections is as high as possible. In particular, many effects and
secondary corrections look significantly better when Color is set to render at higher bit
depths. For more information, see
Playback, Processing, and Output Settings .
Basic Color and Imaging Concepts
Color correction involves controlling both an image’s contrast and its color (exercising
separate control over its hue and saturation). This section explains these important imaging
concepts so that you can better understand how the Color tools let you alter the image.
For detailed information, see:
• Contrast Explained
• Luma Explained
• Gamma Explained
• Chroma Explained
• Primary and Secondary Color Relationships Explained
• The HSL Color Space Model Explained
Contrast Explained
Contrast adjustments are among the most fundamental, and generally the first,
adjustments made. Contrast is a way of describing an image’s tonality. If you eliminate
all color from an image, reducing it to a series of grayscale tones, the contrast of the
picture is seen by the distribution of dark, medium, and light tones in the image.
Controlling contrast involves adjustments to three aspects of an image’s tonality:
• The black point is the darkest pixel in the image.
• The white point is the brightest pixel in the image.
28 Chapter 1 Color Correction Basics