RGB color stands for Red, Green and Blue color model. It is an additive color model that is used for creating colors on computer and tv screens. In the RGB color model, colors are created by mixing varying intensities of the three primary colors red, green and blue. Each primary color has values ranging from 0 to 255, where 0 represents no color and 255 represents full saturation of that color.
Black is the absence of color and in the RGB model, it is represented by R=0, G=0, B=0. However, in some applications a very dark gray color like R=40, G=40, B=40 may be used instead of pure black for technical reasons. So when we talk about 255 black in RGB, it refers to the darkest possible black color that can be displayed where the red, green and blue values are all set to 255.
RGB Color Model
The RGB color model is based on the way human vision perceives color. The retina of the eye has three types of color receptors (cones) that respond to red, green and blue light. When light hits the eye, the cones are stimulated to varying degrees depending on the dominant wavelengths in the light. The stimulation levels of the red, green and blue cones are then processed by the brain to produce the perception of different colors.
In the RGB model, each primary color has a range of intensity values from 0 to 255:
– Red: R value ranges from 0 to 255
– Green: G value ranges from 0 to 255
– Blue: B value ranges from 0 to 255
By combining different intensities of the three primaries, a wide gamut of colors can be generated. For example:
– R=255, G=0, B=0 gives pure red
– R=0, G=255, B=0 gives pure green
– R=0, G=0, B=255 gives pure blue
RGB values are generally expressed in hexadecimal notation from 00 to FF rather than decimal 0 to 255. For example, pure red is denoted as #FF0000 instead of R=255, G=0, B=0.
Representation of Black in RGB
In the RGB color model, black is represented by the total absence of light. To generate black, all the component values (R, G and B) are set to their minimum i.e. 0.
So in decimal values, black is denoted as:
– R = 0
– G = 0
– B = 0
And in hexadecimal notation, it is denoted as:
– #000000
Setting R, G and B values to 0 means that none of the red, green or blue light is emitted by the screen, resulting in black.
However, on displays like CRT monitors, setting RGB values to absolute 0 produced a very dark gray color instead of true black. To get blackest black, the RGB values had to be set slightly higher at around 5-10. But with modern LCD/LED displays, RGB 0,0,0 produces true black.
255 Black in RGB
When we talk about 255 black in RGB, it refers to setting the R, G and B components to their maximum value i.e. 255.
So 255 black is represented as:
– R = 255
– G = 255
– B = 255
In hexadecimal notation, it is denoted as:
– #FFFFFF
At first glance, setting all values to 255 seems counterintuitive for generating black color. But in RGB displays, the screen starts with black when no power is applied. The individual R, G and B pixels then emit varying amounts of colored light to create pixels of other colors on the black background.
Setting R, G and B to 255 means applying maximum voltage to all the LED/LCD pixels to emit maximum light. But since the screen cannot physically output that much intensity, it defaults to cutting off all emission resulting in black.
So in summary, 255 black is the maximum color value setting that shuts off light emission rather than the expected full brightness white. This behavior varies across display technologies.
Technical Reasons for Using 255 Black
There are some technical reasons why using 255 black could be preferable over 0 black in certain applications:
– **CRT phosphor glow:** CRT monitors use phosphors to emit light which can persist for some milliseconds after excitation. Using R=0, G=0, B=0 could result in a faint gray glow. Setting values to 255 black completely cuts off the phosphor excitation.
– **LCD crystal twist:** LCD pixels use liquid crystals that can have imperfections in returning back to untwisted state after becoming untwisted. So black pixels with RGB 0 can allow some light bleed. R=255, G=255, B=255 ensures crystals return to fully twisted black state.
– **LED/OLED burn-in:** Long term use of 0 black risks uneven aging of LED/OLED materials. Using 255 black puts less stress on materials by powering off all pixels.
– **Banding artifacts:** In video processing, encoding artifacts can create banding in dark colors. Setting black to 255 avoids banding and quantization errors.
– **True black reference:** In color grading and photo editing, having a true black reference allows better color corrections. 255 black provides the blackest black possible as reference.
255 Black vs. 0 Black
Here is a comparison between 0 black and 255 black in RGB:
| Property | 0 Black | 255 Black |
|---|---|---|
| RGB values | R=0, G=0, B=0 | R=255, G=255, B=255 |
| Hex code | #000000 | #FFFFFF |
| Color produced | Dark gray to full black depending on display | True black |
| Light emission | No light emission | Max light emission that shuts off pixels |
| Technical advantages | None | Avoids phosphor glow, LCD twist, burn-in, banding |
As seen above, while both 0 black and 255 black have similar appearance, 255 black provides some technical advantages and represents the true black color that displays are capable of producing.
Uses of 255 Black
Here are some common uses of 255 black in digital graphics and video applications:
– **Video encoding:** Using 255 black as reference black avoids banding artifacts and color shifts during video compression.
– **Cinema projection:** Film projectors modulate light from white to black. So cinema digital masters use 255 black to turn off light completely.
– **Black backgrounds:** Using 255 black RGB values results in true black backgrounds without hue or light bleed.
– **Dark room VR:** VR headsets in dark rooms need true black to avoid immersion breaking glow or smear. 255 black delivers that.
– **OLED displays:** OLED pixels achieve true black by powering off. So 255 black saves power while displaying black.
– **Graphics software:** Many graphics editors like Photoshop allow selecting 255 black as the darkest color for designs.
– **Printing:** For CMYK printing, 255 black minimizes ink use while maintaining deep black tones.
So in summary, 255 black has several advantages in rendering true black across digital mediums for visual accuracy and technical efficiency.
Conclusion
255 black refers to setting the maximum values of 255 for red, green and blue components in the RGB color model. While counterintuitive, this achieves true black by completely cutting off light emission from pixels. 255 black provides technical advantages over 0 black on displays using technologies like CRT, LCD and OLED. It represents the true black reference color for applications like video processing, graphics design and printing. However, 0 black RGB may still be preferable where power savings matter more than achieving the deepest black. Overall, 255 black has wide utility across digital imaging pipelines to ensure accurate, efficient and consistent representation of the color black.
