RAW image format for digital cameras

Currently, digital cameras are stored in the same format as JPEG and Tiff, as well as raw. What kind of format is raw? Under what circumstances should I use this raw format? What are the advantages and disadvantages?

In fact, raw is not an image format and cannot be edited directly. Raw format is the original recording of the level and level of CCD or CMOS when converting optical signals into electrical signals. It simply does not process any image data inside the digital camera, that is, digital processing of electrical signals directly obtained by CCD and other photographic components. When shooting in JPEG format, parameters such as white balance and saturation are added to the digital camera, and image data is generated and compressed. Raw data is not processed, so it can only be stored in the hard disk. Use raw data processing software attached to a digital camera to convert it into normal image data such as tiff. During the conversion, most of the parameters such as white balance are set by the user at will. The room for adjusting the exposure compensation is larger than JPG/TIF, and the effect is better .. This is the secret to creating your favorite image data. Unlike using image editing software to adjust JPEG image data, image data will never deteriorate.
The arrangement and conversion methods of CCD/CMOS vary from manufacturer to manufacturer, and the raw record method is also different. Only by converting the program provided by the manufacturer into a general image format can the image processing software be accepted.

Raw files are a proprietary format for each camera manufacturer, and are sometimes the proprietary format for each camera of different models. These files are compressed without loss. When a digital camera is exposed, CCD (or CMOS) records the light volume of each pixel based on the level, and then the digital camera converts these electrical signals into corresponding digital signals, generally, it is recorded as 12-or 14-bit data. If the camera records 12 or 14 bits of data, it means that each pixel has a different brightness level of 4096 (12 power of 2) or 16384 (14 power of 2. (Currently, no image chip can record real 16-bit data)

If you select raw as the file storage format, you can use the raw conversion tool to save it as a 16-bit tiff or PSD format for output later. The 12-or 14-bit data recorded by the digital camera can be extended to all 16-bit space. However, if you choose to store files in JPG format, the software in the camera will convert it to the 8-Bit mode, that is, only 256 brightness levels can be recorded. Advantages of raw format:

· Raw files are almost unprocessed and directly obtained from CCD or CMOS. Through post-processing, photographers can maximize their artistic talents.
· The raw file does not have white balance settings, but the actual data has not been changed. That is to say, the author can adjust the color and white balance freely without any loss of image quality.
· Color linearity and filter row and column transformation can be processed more quickly on a computer with a microprocessor, which allows the application of complicated algorithm rules that are not allowed by some cameras.
· Although raw files are labeled with saturation, contrast, and other information, the actual image data has not changed. You can customize an image without having to use one or two preset modes.
· Perhaps the biggest advantage of raw is that it can be converted into a 16-bit image. That is, there are 65536 levels that can be adjusted, which is a great advantage for JPG files. This is important when editing an image, especially when you need to make important adjustments to the shadow area or highlight area.

Advantages of JPG format

· The file is relatively small. This format can be used to hold more photos on the memory card.
· Image quality meets the needs of most applications, such as home photography and news photography.
· Small files can be easily transmitted and published online. This is important to photojournalists.
· Many players do not have time and hobbies for post-processing.
· When most digital cameras record images in raw format, they cannot take photos very quickly, and it is difficult to capture some instant lenses. However, the raw format cannot be recorded in low-end cameras.

Jpg or raw?

In fact, we can think that all digital cameras use the RAW mode, but when we select JPG as the storage format, we will submit the image to the built-in raw Conversion Program in the camera. If we allow raw as the storage format, it means we can make better adjustments to the photos on a complex platform, even if the changes are not good, we can also make adjustments in the future. In other words, the two options are: Do you decide to convert the raw data in the camera now, or do you want to do it on the computer later?

Before JPG files are generated, some important aspects must be determined, such as white balance, contrast, and saturation. The advantage of raw is that these aspects do not need to be considered at the time, there is plenty of time to think about it.

For some photographers (Sports and News), the convenience and speed of use are the best, but not necessarily others. If you want the best image quality, raw is the best choice. Some cameras save both jpg and raw formats at the same time. This is a good choice for photographers, but it also has to occupy additional storage space.

Some people do not like the raw format because it is too large and they need more space. Raw files require larger storage capacity and cheaper storage capacity, as well as excellent decoding and editing software. With the continuous advancement of technology, we believe that raw will be a wonderful tomorrow.