Connections and differences between CCD, CMOS, digital cameras, analog cameras, TVL, PAL, AV, CVBS, etc.

1. Regarding CCD and CMOS:
The primary difference lies in the location and number of ADCs (Analog-to-Digital Converters). In a linear CCD, after exposure, electrical signals are transferred: the charge signal from each pixel in a row is sequentially moved into a row buffer; circuitry at the bottom then guides the signals to an amplifier located beside the CCD for amplification before passing them through an ADC for output. Another type is the area CCD (or array CCD), where each row has its own amplification circuitry, allowing simultaneous ADC conversion of the captured image data across all rows to process a complete image at once. 
In CMOS designs, each pixel is directly connected to an ADC; electrical signals are amplified and converted into digital signals on-site. 
Comparison: CCDs excel at preserving signal integrity during transmission; by collecting signals from every pixel into a single amplifier for unified processing, they maintain image integrity. CMOS manufacturing is simpler and lacks dedicated signal channels, requiring data from individual pixels to be amplified and then integrated. Consequently, CMOS imaging is more prone to "bad pixels" and image distortion. However, due to process compatibility and low power consumption, CMOS is better suited for embedded applications. While image distortion can be compensated for via algorithms, it is important to note that CMOS sensors are highly sensitive to ambient light, necessitating the design of appropriate lighting systems. In essence, there is little need to delve deeply into the technical nuances of CCD versus CMOS; for the end-user, differences in metrics such as sensitivity, resolution, noise levels, and color separation schemes (RGB, CMYK, or RGBE) are often negligible in practical use. There is little functional difference between the two; in recent years, as CMOS technology has matured, even high-end cameras have adopted CMOS sensors. 
2. Understanding Resolution
Resolution: While there are many ways to describe the concept of resolution, it fundamentally refers to the product of the number of pixels in a row and a column. However, interpretation varies depending on the context—such as whether one is referring to displays or image files. Below is a compilation of precise definitions gathered from online sources. Monitor resolution refers to the precision of the screen image—specifically, the number of dots (pixels) a monitor can display. Since all visual elements on the screen—points, lines, and shapes—are composed of individual dots, a higher number of displayable dots results in a finer, more detailed image and allows more information to be displayed within the screen area; consequently, resolution is a crucial performance metric. You can visualize the entire image as a large chessboard, where the resolution is defined by the total number of intersections between the vertical and horizontal lines.
For a screen with a resolution of 1024×768, each horizontal line contains 1,024 pixels, and there are 768 lines in total—meaning there are 1,024 columns and 768 rows of pixels. Resolution is not only related to screen size but is also influenced by factors such as the CRT's dot pitch and video bandwidth. It is closely linked to the refresh rate; strictly speaking, a monitor's "maximum resolution" is defined as the highest resolution it can achieve while operating at a "flicker-free" refresh rate.
In a graphical environment, high resolution effectively shrinks the on-screen image. This explains why selecting a higher resolution results in smaller images on the display; naturally, a 5×5 icon appears smaller when placed on a larger grid.
Resolution is a key parameter for both LCD monitors and traditional CRT monitors. However, due to their differing imaging technologies, traditional CRT monitors offer greater flexibility regarding supported resolutions, whereas LCDs have a fixed pixel pitch, limiting the number of supported display modes. An LCD's "optimal resolution"—also known as its maximum resolution—is the setting at which the monitor produces the best image quality (so you should feel confident setting your LCD monitor to its maximum resolution).
Image resolution refers to the amount of information stored within an image; it is directly related to the image's pixel count. For an image with a resolution of 640 x 480, the total resolution reaches 307,200 pixels—commonly referred to as "300,000 pixels" (or 0.3 megapixels)—whereas an image with a resolution of 1600 x 1200 contains 2 million pixels (2 megapixels). This illustrates that the two numbers defining resolution represent the number of dots (pixels) along the image's length and width. Digital images typically have an aspect ratio of 4:3. 
3. Digital Cameras vs. Analog Cameras
The distinction between these two types of cameras puzzled me for a long time because I used to attribute the difference solely to the choice of image sensor—a completely incorrect assumption.
Difference 1: Output. Regardless of whether a CCD or CMOS sensor is used, if the output signal is digital, it is classified as a digital camera; if it outputs a standard analog signal, it is classified as an analog camera (often referred to as an analog video camera).
Difference 2: Interface. Digital cameras feature interfaces such as USB (for video chatting), FireWire/IEEE 1394 (for high resolution), and Gigabit Ethernet (for network cameras). Analog cameras typically use AV video terminals (signal wire plus ground wire) or S-Video terminals (commonly known as RCA or "Lotus" connectors) to output standard television signals (PAL or NTSC).
Difference 3: Resolution. This is a significant distinction. The image sensors in analog cameras generally maintain a resolution of around 752 (H) x 582 (V), resulting in a pixel count of approximately 410,000. In contrast, digital cameras offer resolutions—referring here to the sensor itself rather than the captured image—that frequently reach the megapixel level (millions of pixels) found in common consumer products. However, this does not necessarily mean that digital cameras have higher imaging resolution than analog cameras. The reason lies in the fact that analog cameras output analog video signals directly to a television or monitor; the resolution of the photosensitive element is linked to the number of scanning lines in the television signal, and since the display medium is fixed, there is no need for analog cameras to employ high-resolution photosensitive elements. In other words, it is not that the resolution of the photosensitive element in an analog camera *cannot* be made high, but rather that there is no necessity to do so. 
4. Photosites and related concepts
A photosite is essentially a tiny light-sensitive point distributed across the photosensitive element. It corresponds one-to-one with the pixel points displayed on a screen or in an image. Naturally, larger photosite sizes are preferable because they offer greater light-gathering capability, resulting in more accurate color reproduction for the individual pixel. However, this creates a series of trade-offs: larger photosites mean fewer points per unit area and a lower total pixel count, which is detrimental to high-resolution image display. Conversely, increasing the size of the photosensitive element itself to accommodate larger photosites reduces manufacturing yields and drives up production costs.
Here is a personal summary:
Why do both analog and digital cameras exist on the market? The primary reason is the volume of output data. This explains why analog cameras are typically used in surveillance and aerial photography for model aircraft; they generally produce files in the MPG format (an extension for video encoded in MPEG-1, capable of compression ratios up to 200:1 and resulting in smaller data volumes than the AVI format). This low data volume facilitates long-duration recording for surveillance cameras and video transmission for model aircraft. Regarding resolution, they are evaluated using different metrics: TVL (Television Lines) for analog and "pixels" for digital. 
What is the explanation for TVL in resolution? 
TVL stands for "Television Lines" and measures the ability to resolve details in the scene being captured. Pixels are tiny dots of various colors; the more pixels there are, the larger and clearer the image can be displayed. Why do these two classification methods exist? This is because their image formation principles differ. 
Images from analog cameras are composed of lines; the image is formed line-by-line to create the final picture. If you look closely at a TVL (TV Line) image, you can see distinct lines. This process mirrors the display principle of traditional televisions—using line scanning—so clarity is measured by the number of lines; the more lines, the higher the definition. While this can be converted to pixel resolution, the resulting pixel value is not particularly meaningful; a higher pixel value does not necessarily mean a "larger" image. Instead, one should look at the line count: a higher line count indicates greater clarity. 
As noted above, analog cameras typically have pixel counts in the hundreds of thousands. This isn't because higher resolutions are technically impossible, but because they are unnecessary; current line counts meet most requirements. Remember, analog cameras aim for a balance of low data volume and clear imagery. "1080p" refers to progressive scanning with 1080 lines, while "540i" refers to interlaced scanning (also involving 1080 lines). 
Digital camera images are composed of individual pixels, which form the image unit by unit. Terms like "1080p" or "1080i" regarding resolution actually originate from analog camera terminology. 
However, some modern cameras use hybrid modes: they capture digital signals but convert them to analog signals for output based on line counts.
5. Relationships and differences between AV, CVBS, audio, and S-Video signals. 
"AV signal" is a collective term for video and audio signals. When separated, they typically consist of three cables: yellow for video, and red/white for right/left (R/L) audio. The video component (the yellow cable) is known as a CVBS signal; it carries no audio. This explains why single-connector analog cameras typically have only two output cables: a yellow video cable (CVBS) and a black power cable. A bundle of three cables is referred to as an AV cable. CVBS outputs an analog video signal, whereas HD-SDI outputs a high-definition digital video signal, which requires a monitor capable of displaying SDI video. Another option is S-Video (also known as the S-terminal); it carries only the video signal and no audio. It is commonly used with projectors and LCD televisions, often sharing the audio input terminals with AV connections. The reason for using S-Video instead of CVBS is that it transmits the luminance (brightness) and chrominance (color) components separately, thereby avoiding the interference between them that occurs when transmitting a composite video signal.
6. The relationship and connection between the PAL and NTSC standards.
PAL and NTSC are video standards—literally referring to the methods used to produce video, such as resolution and frame rate; notably, they are distinct from the physical connection types mentioned earlier, like AV or S-Video. PAL supports a resolution of 720x576 (Horizontal x Vertical), while NTSC supports 760x480. Both standards apply to analog signals. However, as these resolutions are fixed, standards began to evolve with the advent of high-definition (HD) and LCD televisions; for instance, 1080p utilizes the HDTV standard, though it remains backward-compatible with PAL and NTSC video formats.