Noise

Noise in digital cameras is also referred to as noise and noise. It mainly refers to the rough part of the image generated by CCD (CMOS) in the process of receiving and outputting light as a received signal, and also refers to an image that should not appear in the image. Pixels, usually generated by electronic interference. It looks like the image is dirty, covered with tiny, rough spots. The digital photos we take at ordinary times may not be noticeable if we look at the high-quality images taken by the personal computer after we zoom out. However, if the original image is enlarged, the original color (false color) will appear. This false color is the image noise.

In addition to noise, there is a kind of noise that is easily confused. This is the bad point. Under the same setting conditions of the digital camera, if the noise in the photographed image always appears in the same position, it means that there is a bad point in the digital camera. Generally, the number of bad pixels is regulated by the manufacturer. If the number of bad pixels exceeds The prescribed amount can be changed to the dealer and the manufacturer. If the noise points do not appear in the same position, it means that these noise points are due to the noise generated during use.

The reason for the noise:

1. Image Noise Produced by Long Time Exposure This phenomenon mostly occurs when shooting night scenes. In the dark night sky of the image, there are some isolated highlights. It can be said that the reason is due to the enormous workload of the CCD that cannot handle slower shutter speeds, resulting in some specific pixels losing control. In order to prevent such image noise, some digital cameras are equipped with a function called "noise reduction."

If noise reduction is used, digital processing is used to eliminate image noise before recording the image, so it takes a little extra time before saving.

2. Image Noise Generated by Compressing Images in JPEG Format Because images in the JPEG format still look natural after reducing the image size, special methods can be used to reduce the image data. At this point, it will be processed by one unit above and below 8×8 pixels. Therefore, an unnatural coupling with the next 8×8 pixel unit occurs particularly at the 8×8 pixel edge position.

The image noise generated by the JPEG compression format is also called block noise (Block Noise), the higher the compression ratio, the more obvious pattern noise.

Although this noise becomes invisible even after the image is reduced, after performing the enlargement printing, the color compensation becomes very obvious. This kind of image noise can be solved by using the image quality as high as possible or using methods other than the JPEG format to record images.

3. Image noise caused by fuzzy filtering Image noise caused by image filtering is the same as JPEG image noise caused by image processing. Sometimes it is generated during the internal processing of the digital camera, and sometimes it is generated when the image processing software is used to process it. For a smaller image size, image noise may occur when the color edge is emphasized to make the image appear sharper.

The so-called clear process refers to a digital camera with a color-enhanced image edge features and image editing software "fuzzy filter (Unsharp Mask)" function. There are also some cameras in different models of digital cameras that emphasize the color edges of the entire image. After processing, color lines of other colors appear outside the original edge.

If the image is reduced in size and used on the Internet, does the image always feel blurred? At this point if you use the "fuzzy filter" function to clear the image, the image will look better. However, since image noise is generated, such image noise is troublesome in the second or third processing. Do not make the image appear too rough due to over processing.