bits used for an RGB color is typically called the color depth. Geometric representation Since colors are usually defined by three components, not only in the RGB model, but also in other color models such as CIELAB and Y'UV, among others, then a three-dimensional volume is described by treating the component values as ordinary Cartesian coordinates in a Euclidean space. For the RGB model, this is represented by a cube using non-negative values within a 0–1 range, assigning black to the origin at the vertex (0, 0, 0), and with increasing intensity values running along the three axes up to white at the vertex (1, 1, 1), diagonally opposite black. An RGB triplet (r,g,b) represents the three-dimensional coordinate of the point of the given color within the cube or its faces or along its edges. This approach allows computations of the color similarity of two given RGB colors by simply calculating the distance between them: the shorter the distance, the higher the similarity. Out-of-gamut computations can also be performed this way. Colors in web-page design Initially, the limited color depth of most video hardware led to a limited color palette of 216 RGB colors, defined by the Netscape Color Cube. The web-safe color palette consists of the 216 (63) combinations of red, green, and blue where each color can take one of six values (in hexadecimal): #00, #33, #66, #99, #CC or #FF (based on the 0 to 255 range for each value discussed above). These hexadecimal values = 0, 51, 102, 153, 204, 255 in decimal, which = 0%, 20%, 40%, 60%, 80%, 100% in terms of intensity. This seems fine for splitting up 216 colors into a cube of dimension 6. However, lacking gamma correction, the perceived intensity on a standard 2.5 gamma CRT / LCD is only: 0%, 2%, 10%, 28%, 57%, 100%. See the actual web safe color palette for a visual confirmation that the majority of the colors produced are very dark. With the predominance of 24-bit displays, the use of the full 16.7 million colors of the HTML RGB color code no longer poses problems for most viewers. The sRGB color model (a device-independent color space) for HTML was formally adopted as an Internet standard in HTML 3.2, though it had been in use for some time before that. All images and colors are interpreted as being sRGB (unless another color space is specified)