Image Signal Processors (ISP) of Mobile Camera - Myphontech

Nowadays, cameras are becoming a very important aspect when looking to buy a smartphone with good photography quality.

Understand the working mechanism of the camera and its processor:

We will talking  about one of the most important parts of the camera, which is the ISP   Image Signal Processor ,But before that we get to know the basic components of the camera.

Basic Camera Components:

The Camera machine consists of three basic elements:

1.  Lens
2.  Sensor
3.  Processor called (ISP)  Image Signal Processor

The main function of the lens is to focus the light on the sensor, The larger the opening  the more light it lets into the sensor ,that useful especially in night photography.

The Sensor captures the photons that strike it then converted them into an electrical signal that the camera's processor isp  reads and interprets as colors and at the end your photo will be built and saved.

Camera sensor Characteristics: 

There are many variables that affect the Camera sensor Like the technology used in it is it CMOS or CCD

(CMOS sensors are faster than their CCD and require less current and voltage to operate ), The most common feature of this sensor is the number of pixels,But The most important point is the size of sensor, Bigger size sensors have bigger pixels which means better low-light performance, reduced noise, good dynamic range, and the ability to obtain more information.

Example Specs of standard camera for Huawei p30 pro:

Sensor  from Sony ( Sony IMX650 Exmor RS) technology CMOS BSI ,Lens Aperture f/1.6 , Sensor Size 1/1.7 and Pixel Size 1um.

 standard camera of Huawei p30 pro,Specs

The Image Signal Processor (ISP):

ISP or  Image Signal Processor  is a special type of DSP (Digital Signal Processors) intended for processing image signals , located  inside SoC 'System on Chip' or 'Mobile Processor' .

It works with logarithms in order to form an image that corresponds to reality. 

The 5 Main Tasks of ISP Image Signal Processor:

the ISP performs 5 Main tasks;

-1) Demosaicing Operation: 

The isp use demosaicing or  debayering algorithm  to reconstruct a full color image from  sensor (because sensor just senses photons) interpolate  to RGB for each pixel.

-2) 3A Algorithm :

This name is an abbreviation of three basic operations that the ISP performs using logarithms,

3A = Autofocus(AF) ,Autoexposure(AE),  Autowhitebalance(AWB)

these 3 Algorithms and formulas are based on perceptions of the human eyes.

 -3) Camera LENS Corrections :

Correction for Lens imperfections like Lens shading , Distortion (Geometry) , Vignetting 

where Distortion  appears as otherwise straight lines bending inwards or outwards and Vignetting  appears as a progressive darkening toward the edges of the image. 

-4) Noise reduction (NR):

The ISP use an Noise reduction algorithm that reduced apparent noise in a photo especially with High Dynamic Range HDR .

-5) Control CMOS Sensors:

All smartphones today have multiple rear cameras dual, triple or quad , in reality are sensors with a different lens (wide, macro) that can work separately in Pro mode or work together to enhance your photos,The isp is responsible for all of this.

List of the most famous ISP  (Image Signal Processor)  Manufacturers For Mobile Phone:

•  Qualcomm Spectra™ ISP 
• MediaTek  Imagiq™ ISP 
•  Samsung Exynos ISP 
•  ARM's ISP
•  Google Pixel Visual Core (PVC)
•  Apple ISP 
•  Huawei ISP 

Conclusion:

Noted that the isp processor needs good software to achieve better results This is what distinguishes Google Pixel series.

Thus with the arrival of AI and deep learning (NPU processor ) image processing becomes more complex (ISP work together with NPU) to get incredible results (like Bokeh effect in Galaxy S20 series) and mores others Effects.