Bit rate

Bit rate, generally the higher the bitrate the higher the image quality of the video output. Modern codecs like H.264 will look noticeably better at the same bitrate vs. older codecs like H.263, and variable bitrate (VBR) will look better than constant bitrate (CBR) in most applications.

Keep in mind, there are 8 bits in a byte. So 1 megabyte per second would be 8 megabits per second (mbps). For reference, HD Blu-ray video is generally around 20mbps, standard definition DVD around 6mbps, high-quality web video about 2 mbps, and video for phones in the kilobit range (kbps).

Explanation on bit rate

Bit Depth

Bit depth quantifies how many unique colors are available in an image's color palette in terms of the number of 0's and 1's, or "bits," which are used to specify each color.

This does not mean that the image necessarily uses all of these colors, but that it can instead specify colors with that level of precision. For a grayscale image, the bit depth quantifies how many unique shades are available. Images with higher bit depths can encode more shades or colors since there are more combinations of 0's and 1's available.

Every color pixel in a digital image is created through some combination of the three primary colors: red, green, and blue. Each primary color is often referred to as a "color channel" and can have any range of intensity values specified by its bit depth.

The bit depth for each primary color is termed the "bits per channel." The "bits per pixel" (bpp) refers to the sum of the bits in all three color channels and represents the total colors available at each pixel. Confusion arises frequently with color images because it may be unclear whether a posted number refers to the bits per pixel or bits per channel. Using "bpp" as a suffix helps distinguish these two terms.

Most color images from digital cameras have 8-bits per channel and so they can use a total of eight 0's and 1's. This allows for 28 or 256 different combinations—translating into 256 different intensity values for each primary color. When all three primary colors are combined at each pixel, this allows for as many as 28*3 or 16,777,216 different colors, or "true color." This is referred to as 24 bits per pixel since each pixel is composed of three 8-bit color channels. The number of colors available for any X-bit image is just 2X if X refers to the bits per pixel and 23X if X refers to the bits per channel.

24 bbp

16 bbp

8 bbp

The difference between 24 bpp and 16 bpp is subtle, but will be clearly visible if you have your display set to true color or higher (24 or 32 bpp).

The following table illustrates different image types in terms of bits (bit depth), total colors available, and common names.

Bits Per Pixel	Number of Colors Available	Common Name(s)
1	2	Monochrome
2	4	CGA
4	16	EGA
8	256	VGA
16	65536	XGA, High Color
24	16777216	SVGA, True Color
32	16777216 + Transparency
48	281 Trillion

Resolution

Resolution refers to the sharpness and clarity of an image. The term is most often used to describe monitors, printers, and bit-mapped graphic images.

                                     

For graphics monitors, the screen resolution signifies the number of dots (pixels) on the entire screen. For example, a 640-by-480 pixel screen is capable of displaying 640 distinct dots on each of 480 lines, or about 300,000 pixels. This translates into different dpi measurements depending on the size of the screen. For example, a 15-inch VGA monitor (640x480) displays about 50 dots per inch.