Image processor

The image processor - also known as image processing engine, image processor or image processing system - is one of the most important components of a digital camera. Next to the lens and the image sensor, it plays an important role in the production of the digital image. The photodiodes of the image sensor sees only shades of gray. To obtain color information, the individual pixels with color filters for red, green and blue ( RGB) are provided. These filters are usually placed after the Bayer matrix, ie, next one red, one blue one has two green pixels. Since each photodiode records only the color information for a pixel exactly, would be seen without image processor next to each red and blue pixel two green.

The image processor is a combination of hardware (processors ) and software ( algorithms). He calculates, for example on the basis of information furnished by the image sensor data on the chrominance ( hue and saturation ) and luminance ( brightness ) of the individual pixels, the correct color and brightness values ​​for each pixel. The better the algorithms used, the more natural the colors and the more balanced the contrast.

This process of image data processing is extremely complex and involves many different processes. Its success depends largely on the "intelligence" of the algorithms used. The main features of the digital image, the image processor decisively influences are:

Color representation

The image processor analyzes the color and brightness values ​​of each pixel and compares the information with those of the adjacent pixels. A complex algorithm calculates the correct color and brightness of each pixel. At the same time, the image processor analyzes the entire image to determine the correct distribution of contrast. By adjusting the gamma value ( increase or decrease the contrast range of the midtones of the image) are fine gradients - such as the human skin or the blue of the sky - represented more realistically.

Noise Reduction

As noise disturbances are called, occur in all electronic circuits. On digital photos to image noise shows in the form of irregularly occurring pixels that differ in color and / or brightness of the surroundings. Is reinforced by the effect of higher ambient temperatures, longer exposure times or higher ISO settings.

At high ISO values ​​( = high sensitivity of the sensor), the electronic signal is raised in the image sensor and thus simultaneously amplifies the noise, thereby improving the signal -to-noise ratio decreases. The image processor tries to separate image and interference from each other and thus to suppress the noise. This is particularly difficult in image areas with fine textures. If these are erroneously regarded by the image processor as noise and treated, they lose drawing.

Smooth and sharp edges

After the color and brightness values ​​were interpolated for each pixel, the image processor records the recording something soft to compensate for any color variations in individual pixels. In order to receive a sharp and detailed image, and then edges and contours are sharpened. The quality of the result depends on how well the image processor detects edges and this reproduces smooth and without sharpening.

Speed

Especially given the ever-increasing megapixel count of digital cameras, the processing speed of the image processor is increasingly important. In order to eliminate waiting times in the workflow as possible, so they must be continuously improved in terms of their speed.

The image processors from different manufacturers have various names:

Canon - DIGIC Nikon - EXPEED Olympus - TruePic Panasonic - VENUS Engine

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