Depending on the context a 0x or a number sign (#) is put before the hex digits. In cases where the alpha is not used this can be shortened to 6 digits RRGGBB, this is why it was chosen to put the alpha in the top bits. The 80 hex value, which is 128 in decimal, represents a 50.2% alpha value because 128 is approximately 50.2% of the maximum value of 255 (FF hex) to continue to decipher the 80FFFF00 value, the first FF represents the maximum value red can have the second FF is like the previous but for green the final 00 represents the minimum value blue can have (effectively – no blue). For example, 80FFFF00 represents 50.2% opaque (non-premultiplied) yellow. The channels are arranged in memory in such manner that a single 32-bit unsigned integer has the alpha sample in the highest 8 bits, followed by the red sample, green sample and finally the blue sample in the lowest 8 bits:ĪRGB values are typically expressed using 8 hexadecimal digits, with each pair of the hexadecimal digits representing the values of the Alpha, Red, Green and Blue channel, respectively. In many systems when there are more than 8 bits per channel (such as 16 bits or floating-point), the channels are stored in RGBA order, even if 8-bit channels are stored in some other order. On a little endian architecture this is equivalent to ABGR32.
RGBA 255 255 255 1 PORTABLE
In OpenGL and Portable Network Graphics (PNG), the RGBA byte order is used, where the colors are stored in memory such that R is at the lowest address, G after it, B after that, and A last. This article will use a scheme that has some popularity, which is to add the suffix "8888" to indicate if 4 8-bit units or "32" if one 32-bit unit are being discussed. Therefore, to be unambiguous, it is important to state which ordering is used when referring to the encoding. This is not the case for a little-endian system, where the two mnemonics are reverses of each other. In a big-endian system, the two schemes are equivalent. In the word-order scheme, "RGBA" is understood to represent a complete 32-bit word, where R is more significant than G, which is more significant than B, which is more significant than A.This scheme is commonly used for describing file formats or network protocols, which are both byte-oriented. In the byte-order scheme, "RGBA" is understood to mean a byte R, followed by a byte G, followed by a byte B, and followed by a byte A.There are two typical ways to understand a mnemonic such as "RGBA":
The interpretation of these 4-letter mnemonics is not well established.
These encodings are often denoted by the four letters in some order (e.g.
The order of these four bytes in memory can differ, which can lead to confusion when image data is exchanged. By far the most common format is to store 8 bits (one byte) for each channel, which is 32 bits for each pixel. In most cases four equal-sized pieces of adjacent memory are used, one for each channel, and a 0 in a channel indicates black color or transparent alpha, while all-1 bits indicates white or fully opaque alpha. In computer graphics, pixels encoding the RGBA color space information must be stored in computer memory (or in files on disk).
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