The main part of our eye is Retina, which is located here..If we look at the structure closely, inside the retina, we can find 126 million photoreceptors: consists of Rod and Cones cells.Photoreceptors plays an important part, since its task is to converts light that enters our eye into neural electrical signals – and bring it to optic nerve transport to the visual cortex of the brain to be interpreted.
We can see in this picture that the people is ….So, photoreceptors in retina is very..very.. crucialTherefore, we should come up with the solution to help this people by implementing a complete vision system in a single chip…
In the latest development, retina prosthesis is implanted to the retina. With this device, the light information can be converted to electrical signal and trigger the ganglion cells to bring the pulse to the brain. Then, the patients learn how to interpret these visual patterns. This is only an example of the retina chip application. Nowadays, the Retina SoC is widely used in industrial sector, such as vehicles, robotics, etc.
now we understood that the task of the System on chip retina is for image….Thus, the main challenge of SoC Retina is to integrate in the same circuit the acquisition photo-sensors and some processing elements. Also, the process must be in highly parallel to achieve real-time image processing.Programmable means, the chip can perform various vision function
As we know, Retina chip only does the Low and Medium Image processing..Here is some results of those process from inside the retina..First, Grayscale Morphology.. To smooth this letter ‘A’ and fix some disconnect in the image, using opening and closing operation. Which only takes 80.2 micro seconds.Next, the Binary Morphology.. Which is performed by the Processing Element array in pixel-parellel, with thining operation until it results the ‘skeleton’ of this letter.After that, the chip can perform 1,000 frame per second target tracking.. The skeleton of the object is used for calculation the coordinates. So from these 3 samples, the chip can track the moving targets and provide its centroid coordinates.Indeed, these kind of process may be useful in robotic vision application.
This is one example of the basic diagram block of the retina chipOne pixel contains of one processing element with one photodetector inside of it.… doorway: since its function is to convert the light into electrical signals.Photo detector ~ like photo receptor in retinaThese circuit is fabricated using CMOS technologyCommonly, the SoC Retina is fabricated using CMOS technologySince it can mime the synapses for having the high connectivity .Low cost and high resolution
How does this retina chip work?The image is focused on the chip through the lens. The chip consists of array of pixel. In a single pixel, photodetectors detect the sensitivity. Then there it performs a readout mechanism to be processed by the processor circuit, to perform a low-level image processing. Then, it outputs processed images.
There are various application of SoC programmable retina. 1. It can be used in retinal prosthesis to help certain blind people to partially regain their vision, especially for those people who lose their vision in accident rather than those born blind. (visual implant 2006)2. It can also be used in the Intelligent security and surveillance systems. It can track target in high speed. 3. Besides, it is used in industrial machine vision and robotics for rapid inspection of a product.
A visual prosthesis is an artificial organ to restore the sight of blind patients with electrical stimulation to the visual nervous system. The video shows the image which the patient perceived while observing his hand with visual prosthesis . This visual prosthesis consists of an extra-ocular and an intra-ocular device which contains various technologies such as image capture and processing, wireless data & power transmissionon a singleIC. According to the visual information captured by a video camera in the extra-ocular device, the information is coded, then sent to the intra-ocular device through an infrared (IR) communication unit. After the intra-ocular device receives the IR data, it generates adequate electric pulses for stimulating the retina. (2004)
Another interesting application of the SoC programmable retina is in the intelligent car system. The artificial retina cards are placed in front of the car integrating in the complicated system of a intelligent car. With its fast response, it could prevent collision by sensing approaching car and obstacles.
Another application of SoC Programmable Retina is human/multimedia interface, such as interactive game. As an artificial retina module and the game screenis placed in front of a player. Artificial retina module detects body movement from the player & translate them into the character’s action on the screen instead of getting user input from conventional joystick or keyboard. The required time for image detection, recognition and feedback to the game character is less than 16 msec. (1997)Algorithm based on optical flow model.
Retina Chip- Basic Architecture1 PE (Processing Element) + 1 photo-detector= 1 pixelMimic HumanRetina?Photo detector ~ Photo-receptor(in human retina)• Doorway to SoC chip• Large dynamic rangeCMOS technology ~ Synapses (inhuman retina) Photo- Block diagram of detecto the retina chip• High connectivity r• Ease integration with PE on thesame chip
SoC & Programmable Retina System• Four components of Retina Circuit: – Phototransduction obtain analog value of the image – Analog Processing spatio-temporal filtering – A/D Coding • NISP (Near Image Sensor Processing) • Digitize the analog value through multiple thresholding – Digital Processing • The SIMD machine, made of digital processor meshes • Process Boolean planes (binary image) data
Conclusion Power Consumption, Size, Cost, Real-time efficiency are main issues in this field SOC programmable retina integrate parallel processing with sensing reduce size and cost Low power dissipation Autonomous decision making from real-time analysis Promising application in various areas
References Paillet, D.Mercier, T.M.Bernard and E. Senn, "Low power issues in a Programmable Artificial Retina", Proc. IEEE Workshop on Low. Power Design, pp.153-161, 1999. Lin Q, Miau.W,, et al. A 1,000 Frames/s Programmable Vision Chip with Variable Resolution and Row-Pixel-Mixed Parallel Image Processors. 2009. ISSN 1424-8220 Elouardi A, Bouaziz S, Dupret A, Klein J O and Reynaud R. 2004. On chip vision system architecture using a CMOS retina Proceeding. A. Manzanera. Morpholigical Segmentation on the Programmable Retina: Towards Mixed Synchronous/Asynchrounous Algorithms. in ACM ISMM Conference. K Kyuma, Y.Nitta, Artifical Retina Chips for Image Processing. 1997. Artif Life Robotis 1: 79 – 87.