ronvp wrote:Why you do not do your homework and stop arguing is beyond me. .checked out several bit rate calculators, and the all show that when you change color model, the bit rate changes.... maybe they are all wrong and you are the expert (or maybe not!)..
Yes, I have done my homework. Perhaps you should do the same. I guarantee you anybody that says color space or color model changes the uncompressed bitrate is flat out wrong. It absolutely does not happen. Clearly the people that wrote the stuff you are reading do not know WTF they are talking about. Either that or you don't understand what they are saying. Both are plausible explanations.
If you want the truth, I'll try to make it simple. To express a color, you need to know two things:
- The color model, which defines how to express colors. Essentially, this is the "language" that must be agreed upon between the transmitting device and the receiving device. Once the language is agreed upon, the receiving device will know what each bit of color information actually means. If the two devices don't agree on the same language, the receiving device will misinterpret the data coming from the transmitting device, and thus a command to make a pixel a certain color will result in the pixel being some other color instead. Two generic examples of this would be an adaptive color model (where colors are added together to get other colors) and a subtractive color model (where colors are subtracted from each other to get other colors).
- The color space, which defines what colors from the color spectrum can actually be expressed. Additionally, each color space also has its own distribution of colors.
The only thing the color model and color space do is translate bits of data (1's and 0's) into actual colors. In other words, they both define
what the bits of data actually mean. But neither of those things define how much data is required to express a particular color. That is where color depth comes in. The color depth is a measure of precision. For example, a 1-bit color depth means 2 colors can be expressed (color 1 and color 0), but not any other colors. Which two colors can be expressed depends on the color model and color space. Perhaps in color model A, 1 means red and 0 means black. But in color model b, 1 means green and 0 means purple. The particular color model and color space used do not change the fact that there is still only one bit of data used to express the colors.
To increase the number of colors that can be expressed, you would want to increase the number of bits used to express colors. While a 1-bit color depth is only able to produce 2 colors, a 2-bit color depth can express 4 colors (color 00, color 01, color 10, and color 11). Again, which 4 colors depends on the color model and color space, and the specific color model and color space used does not change the fact that 2-bits are still used to express colors. But the color model and color space define which specific colors are being expressed by the 2-bits.
You can continue increasing the color depth as high as you want. The more bits that are used, the more precise you can be in expressing a certain color. But in no case does changing the color model or color space translate into any change in how many bits are used to express each color. In all cases, 24-bit color depth (aka 24-bit precision) means that 24 bits are used to express colors.
So again, it is absolutely impossible for a 24-bit color depth to require any more or less than 24 bits to express a color, regardless of what color model or color space is being used, and anybody that says it does is completely wrong.