Living in the era of digital camera flooding, almost has to forget the concept of "negative film". Those who have played film have actually restored the film negatives. Maybe many people think that it is called real film processing. In fact, in today's digital age, we still retain the negative film concept. That is, "digital negatives" is What? It's just an unprocessed raw packet, which is the RAW storage mode. Everyone knows that the film can only be fixed once, and the familiar JPEG image is equivalent to the fixed film, while RAW is equivalent to the exposed film in the cassette, but it is more controllable and post-processing. The space is bigger.
· What is RAW, what is JPEG
To understand the RAW storage mode, you must first understand the actual imaging process of the digital camera.
When we press the shutter, the light is irradiated onto the photosensitive element of the camera through the lens, and the photosensitive element converts it into an electronic signal that forms image data. These electronic signals are directly stored in the image file format without any processing. A RAW format file is formed. Simply put, RAW reflects the most primitive information packets from the image sensor, not the image. Let's talk about the JPEG format image that we are used to. It is the preset white balance, exposure compensation, contrast, saturation, color mode and dynamic range of the RAW file when it is taken by the camera through the camera's built-in image processor. Set the image obtained by the compression process. To put it bluntly, no matter which format we use, the camera captures the original image data, and all we can choose is whether the raw data should be handed over to the camera for processing in JPEG format, or saved as RAW format.
The principle of digital camera imaging
Speaking of RAW, we need to understand a technical term, called color depth. The unit of color depth is bit. The color depth of ordinary jpg photos is 8bit, which means that the three colors of RGB, each color has 256 levels, which can be combined to produce a total of 256*256*256 or about 16.77 million different colors. Color, which is the display limit of current mainstream display devices, is quite sufficient in most cases.
8bit/14bit color depth effect comparison (schematic)
Is there anyone to ask, is the RAW format file taken by all cameras the same? I can tell you that it is different. The standards of different brands for products are not the same, and even the standards used by cameras of different models of the same brand are different. As far as Canon is concerned, although the RAW file suffix is .CR2, there are still some differences between the 1100D and 7D RAW files.
· RAW has advantages and disadvantages
RAW files contain more image information and richer tone than JPEG, providing a wider space for later, such as white balance, sharpness, saturation The parameter information such as degree can be finely adjusted in post-processing, which can help us establish a series of fine parameters such as exposure and color temperature that are not well mastered. In addition, the advantage of the RAW file is that it preserves richer highlight and shadow details, and provides better white balance control, so it is more convenient when recording scenes with high contrast, while still reducing the details of the shadows. Maintain a relatively high picture quality and arbitrarily change the settings of the photo after shooting.
JEPG format image imaging is more solid, and the clarity and exquisiteness of the picture are improved, and the details of the picture are also more abundant. Because the RAW format records all the information received by the photosensitive element, it will be superior to the JEPG format file that has undergone "lossy compression".
JEPG and RAW quality comparison
There is a saying that is good: there are advantages and disadvantages. Although RAW files contain more image information than JPEG, and have a wider back space, RAW files are very troublesome to browse and output. They must be converted by related software, and the conversion process is somewhat cumbersome for beginners. . In addition, RAW files take up a lot of storage space, so if you shoot, you need to prepare a larger capacity memory card.