Experience of IPC image debugging in HiSilicon platform

DRC:

When turned on, it increases the dark details and also increases the noise, resulting in a greater noise intensity than when the DRC is turned off, where the edge enhancement and de-noising function should be related to the DRC

Ae:

1: Exposure time: Sensor accumulates charge time, is the sensor pixel from the beginning exposure to the power is read out of this
Period of time.
2: Exposure gain: The total amplification factor of the output charge to the sensor, typically with a digital gain and analog gain, the analog gain introduces a slightly smaller noise, so the general priority is to use the analog gain.
3: Aperture: Aperture is a mechanical device in the lens that can change the size of the middle hole.
4: Anti-flicker: due to the lamp power frequency and sensor frame rate mismatch caused by the picture flicker, general
Limit exposure time and modify the frame rate of the sensor to achieve a flicker-resistant effect.

Sharpen:

In different illumination, the same object detail, edge performance is not the same, in order to balance the authenticity and object details
performance, adjusting parameters with illuminance changes. At the same time at low bit rate, due to the high coding pressure, can be properly reduced
Edge strength and detail of the object to ensure the coded motion effect at low bit rate

Sharpenaltd, the big edge, the increase will cause the white edge is obvious, but looks very sharp. Sharpness of edges
The definition of large edge is an important factor to affect people's subjective feeling

Sharpenaltud, details. Increased noise increases, which is recommended under low illumination
Lowered.

Noise and bit rate
1. Large noise and relatively small bit rate, increase the noise intensity, can effectively reduce the coding pressure
To make the image more effective.
2. Do not mistakenly think that ambiguity is caused by noise. A lot of things blur because of the coding loss.

The 3.Sharpen is based on the Demosaic parameter. The Demosaic parameter identifies
Edge, and then by sharpen

The color temperature of some common light sources is: The standard candle is 1930K (Kelvin temperature unit), the tungsten lamp is 2760-2900k, the fluorescent is 6400K, the Flash is 3800K, the noon Sun is 5000K, the electronic flash is 6000K, the blue sky is 10000K. So the evening color temperature is the highest, suitable for testing

Dci:

is the abbreviation for automatic contrast enhancement (Dynamic contrast improvement). Based on the brightness of the current image
Distribution, dynamically adjusts the brightness and contrast of the image. Due to the environmental impact, the captured images are often
There is a case of dark, light-biased and low contrast. DCI will lighten the brightness of the image, dim the image brightness
Increase the contrast of the monotone image and reduce the contrast of the image with too much brightness change

Note:

DCI automatically adjusts for brightness, contrast, and usually does not need to adjust 3 gain values to avoid adjustments due to gain
Improper, causing the image to be too bright, too dark and less contrast or too strong, and to increase the human eye of the original invisible details,
or lose visible detail. The 3 gain provides a dynamic contrast adjustment based on the value of the manual intervention that can be superimposed. 3
Parameters are independent, can be set separately, there is no mutual restriction between the parameters, the effect of debugging and the specific field
In different scenarios, adjust the above 3 gain values, the effect will not be exactly the same

Gamma:

1. Gamma has a significant effect on image quality, and different gamma curves can take
have different effects.
2. Gamma affects contrast and dark details. The higher the contrast, the better the permeability,
But the more the corresponding dark details are lost.
3. Gamma also has an effect on color. The higher the general contrast of the gamma curve, the fuller
And the higher the degree

4. The lower the front half of the curve, the higher the contrast

5. Low-light, high-contrast gamma will make the screen appear less noise, more clarity
Good

6. High contrast gamma dark lost much, and dynamic configuration gamma table for CPU consumption
Big. Consider this carefully.

Factors affecting clarity:
1. Optical filter
Effect of filter on resolution: Some filters have OLPF (optical low-pass filtering) function, which will reduce the level of resolution
or vertical resolution, the degree of reduction in horizontal and vertical resolution varies, mainly by the direction of OLPF, OLPF
The directions are divided into three categories: horizontal, vertical, horizontal and vertical. OLPF with horizontal direction of the filter pair
The horizontal resolution affects the vertical resolution of the OLPF filter with vertical direction, while the vertical side
Directional and horizontal OLPF have an effect on both horizontal and vertical orientations. No OLPF function of the filter to the resolution of the
Have an impact.
2. Lens
Effect of lens on sensor: When the sensor resolution is greater than the resolution of the lens, the maximum resolution of the image is the lens
The resolution. For example, a 1080p sensor needs a lens resolution greater than 2M, or the resolution will be reduced. Because
The resolution of the lens must not be less than the sensor resolution

3.Demosaic as an ISP image processing module, the configuration of the relevant parameters will also affect the resolution of the image

4.Sharpen, Denoise

The intensity of sharpening and de-noising follows the gain connection.

5. In many cases, clarity and noise are contradictory concepts that can only be weighed against preferences.

Gain large scene:

1. For the gain big scene, for the noise effect, can adjust the demosaic/dynamic bad point/gamma

2. Increase the noise, can make the screen clean, but will lead to blur

Drag Shadow:

1. In fact, 3D de-noising and coding can cause drag
3D de-noising is continuous, the coding drag is disconnected

Low Photo:

1. Increase the 2D strength to make the screen cleaner. will cause the screen to look dirty, but 3D
The noise can be made static.
2. Limiting the maximum gain can effectively reduce the noise. And it doesn't make people feel much darker.