Xinsheng IntelligentWritings50 questions about industrial cameras (5)

　41: How to improve the signal-to-noise ratio of the image?

　　The signal-to-noise ratio (SNR) reflects the anti-interference ability of the camera's imaging, and the reflection in the image quality is whether the image is clean and free of noise. The following techniques can improve the signal-to-noise ratio of the image and make the acquired image clearer and cleaner.

　　42: How to improve the dynamic range of industrial cameras?

　　The purpose of camera dynamic range imaging is to correctly represent the wide range of brightness in the real world, from direct sunlight to the darkest shadows. The following techniques can improve camera dynamic range.

　　Techniques to Improve Camera Dynamic Range

　　name

　　Features

　　Technical points

　　logarithmic response

　　Increase the dynamic range of imaging devices

　　Set up a logarithmic video amplifier circuit

　　deep trench technology

　　On the basis of maintaining the advantages of high quantum efficiency of thin CCD, while improving the quantum efficiency of red light

　　Use high-resistance silicon with a thickness of about 40 to make a CCD

　　double exposure

　　Improve the ability of the imaging device to adapt to changes in the target light intensity, suitable for situations where the light intensity changes drastically

　　Make exposure settings for the sensor, automatically use long exposure in low light, and automatically use short exposure in strong light

　　43: How to improve image quality by adjusting industrial cameras?

　　In the machine vision system, the camera needs to collect images, and sometimes the quality of the collected images is average, which requires us to improve the image quality by adjusting some functional parameters of the industrial camera. The following techniques can improve the image quality.

　　Basic techniques for improving image quality

　　name

　　Features

　　Technical points

　　Electronic exposure

　　Eliminate exposure saturation, reduce halo, reduce image blur, extract moving target images

　　Setting the exposure control gate in the photosensitive device

　　anti-halation

　　Eliminate pixel halo, prevent the charge above the full well from overflowing into the believe pixel, and improve the image clarity

　　Shorter exposure time, but sometimes not effective;

　　isolate each pixel from each other;

　　Next to each pixel, a channel of excess photocharge is created

　　Multimode output

　　Linear Mode, Dual Slope Mode, Logarithmic Mode or Y-Correction Mode

　　Set up dedicated circuitry or software for multi-mode output

　　digital zoom

　　Achieving an effect similar to optical zoom, and the image quality is significantly improved

　　Enlarge the image using interpolation

　　white balance

　　Eliminate color distortion and improve image color fidelity

　　Correct the weighting coefficients of the three primary color channels RGB by imaging a standard clapper and a standard light source

　　44: What is the difference between the mechanical shutter and the electronic shutter of the industrial camera?

　　Mechanical shutter: Use springs or electromagnetic means to control the opening and closing of several blades, or two-layer curtains “swipe” through the image field window with a certain width of gaps left and right or up and down like a stage “drawing curtain”, allowing the window Get a "light opportunity" for a specified length of time - this is the usual mechanical shutter concept.

　　Electronic shutter: Control the exposure of the shutter by directly operating the CCD/CMOS through the circuit, which is called the electronic shutter. Using the principle that CCD/CMOS does not work if it is not powered on, under the condition that the CCD is powered off, although the window is "largely open", it cannot produce an image. If the electronic timing circuit is used when the shutter button is pressed, the CCD/CMOS is only energized for "a specified period of time", and the same effect as a shutter "instantly opened" can be obtained.

　　Generally speaking, the advantage of a mechanical shutter is that it can work without electricity, but the disadvantage is that the comparison between high and low gears will be inaccurate. Electronic shutters are more accurate than purely mechanical shutters, have higher performance (minimum exposure times can be shorter, etc.), are more reliable, and have a longer lifespan.

　　45: What is the difference between a digital industrial camera and an analog industrial camera?

　　Conceptually, the two cameras only differ in output signals. The analog industrial cameras output analog signals, and the digital industrial cameras output digital signals. That is to say, the A/D conversion of the analog industrial camera is performed outside the industrial camera, and the A/D conversion of the digital industrial camera is completed within the industrial camera.

　　46: How to maintain the industrial camera?

　　1. Try to avoid pointing the camera directly to the sun, so as not to damage the image sensing device of the camera;

　　2. Avoid contacting the camera with substances such as oil, steam, water vapor, moisture and dust, and avoid direct contact with water;

　　3. Do not use harsh cleaners or organic solvents to wipe the camera;

　　4. Do not pull and twist the connecting wire;

　　5. If it is not necessary, do not disassemble the camera at will, and try to touch its internal parts, which will easily cause damage to the camera, and think that the damage is not guaranteed by the dealer;

　　6. During storage, the camera should be stored in a clean and dry place.

　　47: What is a frame grabber?

　　The frame grabber card, also known as the image card, transmits the image and video signals of the camera to the computer's memory and VGA frame memory in units of frames for computer processing, storage, display and transmission. In the machine vision system, the image collected by the image acquisition card is used by the processor to process whether the workpiece is qualified, the movement deviation of the moving object, and the location of the defect.

　　48: What are the categories of frame grabbers?

　　1. According to the input signal, it can be divided into analog frame grabber and digital frame grabber;

　　2. According to the color of the collected signal, it can be divided into black and white image acquisition cards and color image acquisition cards;

　　49: The relationship between resolution and pixels?

　　Resolution and pixels are proportional, the larger the pixel, the higher the resolution. The higher the pixel, the higher the maximum output image resolution.

　　50: What is the relationship between the size of the CCD/CMOS chip of an industrial camera and the size of the image?

　　The relationship between CCD/CMOS chip size and image size in industrial cameras is as follows:

　　CCD/CMOS size