Bit Depth
Bit depth refers to the number of bits used to represent the color of each pixel in an image or the amplitude of audio samples. In digital imaging and audio, higher bit depth allows for a greater range of colors or sound levels to be represented, resulting in higher quality and more accurate reproduction of the original data.
4 Key excerpts on "Bit Depth"
eBook - ePubIntroduction to Interactive Digital Media
Concept and Practice
- Julia Griffey(Author)
- 2019(Publication Date)
- Routledge(Publisher)
...This presented a challenge for web designers at the time because they had to choose colors and design graphics that wouldn’t look horrible on monitors with limited Bit Depth. The example below illustrates how Bit Depth influences the quality of an image. In the photograph on the right, only 8 bits are being used to describe all of the different colors in the original image. The result is that it looks really splotchy and flat because with 8 bits we can only use 256 unique colors to describe the image, and 256 colors are not enough to capture the broad range of colors that were in the original image. 4.6 Images saved with a limited Bit Depth (256 colors) tend to have flat areas of color A low Bit Depth has a similar, detrimental effect when applied to sound. With a limited number of bits, you cannot precisely describe the level of the sound that you are sampling. The resulting digital sound sampled at a low Bit Depth would be a really distorted version of the original sound. A best practice is to capture and keep digital files in the highest possible resolution, Bit Depth, sample rate, etc., until outputting the final product. Then, if further manipulation is required, or the finished product needs to be higher quality, the original files will allow for it. The Pros of Digital Media Although converting media to digital formats involves making compromises, there are several advantages to having media in a digital form. One major advantage is that it can be reproduced without generation decay. Generation decay would occur when duplicating analog media, such as when recording from one cassette tape to another. The copy would not be as good quality as the original. Another significant advantage of working with media in a digital form is being able to make edits in a nonlinear fashion. Before film editing was done on the computer, editors literally had to cut and tape pieces of film together. If they cut off too much, it was a difficult mistake to fix...
eBook - ePubCompositing Visual Effects
Essentials for the Aspiring Artist
- Steve Wright(Author)
- 2013(Publication Date)
- Routledge(Publisher)
...I like to think this is due in no small part to the vitriolic cries of outraged digital compositors complaining about working with the non-square pixels of NTSC and PAL. Because square pixels have an aspect ratio of 1.0, when the display aspect ratio is calculated by multiplying the image aspect ratio by 1.0 there is no change. The conclusion is that the display aspect ratio and image aspect ratio are the same for images with square pixels. 2.2.6 Bit Depth You have undoubtedly heard that computers only work with ones and zeros. This is literally true. Each one and zero is called a bit (binary digit—get it?), and these bits are organized into 8-bit blocks called bytes. Here is a byte—00000001. Here is another one—11001010. If you group 8 bits into a byte the number of possible combinations of ones and zeros is only and exactly 256, and their values range from 0 to 255. In other words, an 8-bit byte can hold any integer number between 0 and 255. The number of bits being used is what is meant by the term Bit Depth. If the number of bits was increased to 10 we could make 1024 different numbers. If they were reduced to 4 we could only make 16 numbers. The greater the Bit Depth, the more numbers we can make. To relate this back to digital images, if a pixel’s brightness is described by an 8-bit byte then there can only be 256 brightness values ranging from black (0) to white (255). This seems sensible enough. For an 8-bit three-channel RGB image, then, each channel can have only 256 brightness values ranging from 0 to 255. The maximum possible number of different color combinations becomes 256 × 256 × 256 (for all three channels), or about 16.7 million colors. That may sound like a lot of colors, but read on. Modern compositing packages also support 16-bit images. When the Bit Depth is increased from 8 to 16 bits per pixel, we now have a whopping 65,536 possible brightness steps from black to white (0 to 65,535)...
eBook - ePub- Lee Lanier(Author)
- 2012(Publication Date)
- Routledge(Publisher)
...CHAPTER 3 Bit Depths, Color Spaces, and Color Grading A critical component of digital compositing is the proper selection and conversion of color spaces. Failure to take color space into account can lead to composites with mismatched color values or color artifacts. In addition, image formats vary in their fundamental mathematical makeup, leading to additional concerns as files are imported into Nuke and written out to disk. Once the technical aspects of color space and image format conversion are mastered, aesthetic color adjustments remain. Such adjustments fall under the auspice of color grading. Nuke offers a wide range of color filter nodes that allow you to undertake color grading within the program. This chapter includes the following critical information: • Understanding Bit Depth, color space, and look-up tables • Converting between color spaces in Nuke • Differentiating among linear, logarithmic, integer, and floating-point image formats • Color grading with Nuke color filter nodes Understanding Bit Depth Digital images carry three channels: red, green, and blue (RGB). (Other specialized channels, such as alpha, are carried by a limited number of file formats and are discussed throughout this book.) Each channel’s Bit Depth establishes how many potential colors (or tonal steps) that channel can carry. Bit Depths are expressed as a number, such as 1-bit, 2-bit, and so on. The number represents an exponent where the base is 2. For example, 1-bit equates to 2 1 or simply 2. 8-bit equates to 2 8 or 256; hence, an 8-bit image has 256 potential colors per channel for a total of 16,777,216 potential colors (2 8 × 2 8 × 2 8). The number 2 is used as the base because a single bit has two potential states (0/1 or off/on)...
eBook - ePubCompression for Great Video and Audio
Master Tips and Common Sense
- Ben Waggoner(Author)
- 2013(Publication Date)
- Routledge(Publisher)
...So, typically processing is done in groups of 1 byte (8-bit), 2 bytes (16-bit), 4 bytes (32-bit), 8 bytes (64-bit), et cetera. Something that requires 9-bit is going to really be processed as 16-bit, and so can require twice as much CPU power and memory to process. So, you’ll see lots of 8-bit, 16-bit, and 32-bit showing up in our discussion of quantization. We’ll also see intermediate numbers show up, like 10-bit, but those are more about saving storage space over the full byte size; it’s still as slow as 16-bit in terms of doing the calculations. Quantizing video Basic 8-bit quantization, and why it works Continuing our graph paper metaphor, consider a single square (representing a single sample). If it’s a solid color before sampling, it’s easy to represent that solid color as a single number. But what if that square isn’t a single solid color? What if it’s partly red and partly blue? Because a sample is a single point in space, by definition, it can have only one color. The general solution is to average all the colors in the square and use that average as the sample’s color. In this case, the sample will be purple, even if no purple appeared in the original image. See Color Figure C.10 for an example of this in practice. The amount of quantization detail is determined by Bit Depth. Most video codecs use 8 bits per channel. Just as with 8-bit audio systems, 8-bit video systems provide a total of 256 levels of brightness from black to white, expressed in values between 0 and 255. Unlike 8-bit audio (a lousy, buzzy-sounding mess with no dynamic range, and which younger readers may have been fortunate enough never to hear), 8-bit video can be plenty for an extremely high-quality visual presentation...
