.::APHESA SPRL - imaging, electronics and software consulting::.

Publications and blog

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Image sensors technology publications

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Spectral Response of Silicon Sensors
White paper describing the physical properties of silicon and how silicon can see. Large emphasis is made on spectral response first and second order effects.
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From CCDinosaurs to the APS century
Invited Keynote at the 2016 Caeleste workshop in Brussels (part of SPIE Photonics Europe) - about the history of imaging from CCD to CMOS APS devices and a window on the future
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Response Curve Programming of HDR Image Sensors based on Discretized Information Transfer and Scene Information
Most of the snapshot HDR (High Dynamic Range) image sensors have a non-linear, programmable, response curve that requires multiple register settings. The
complexity of the settings is such that most algorithms reduce the number of parameters to only two or three and calculate a smooth response curve that approaches a log response. The information available in the final image depends on the compression rate of the response curve and the quantization step of the device. In this early stage proposal, we make use of scene information and discrete information transfer to calculate the response curve shape that maximizes the information in the final image. The image may look different to a human but contains more useful information for machine vision processing. One important field of use of such sensors with programmable dynamic range is automotive on-board machine vision and more specifically autonomous vehicles.
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EMVA1288 publications

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Using the EMVA1288 standard to select an image sensor or camera
Using the EMVA1288 standard to select an image sensor or camera (Paper presented at SPIE Electronic Imaging 2010, see first page of the document for an abstract)
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Implementing and using the EMVA1288 standard
We have measured cameras of various kinds on our test equipment. The test system design and all the measurement sets require to go in the details of the standard and also show us how good it can be but also how difficult it can be.

The purpose of this paper is to give feedback on the standard, based on our experience of implementers and users. We will see that some measurements are easily reproducible and can easily be implemented while others require more research on hardware, software and procedures and also that the results can sometimes have very little meaning. Our conclusion will be that the EMVA1288 standard is good and well suited for the measurement and characterization of image sensors and cameras for image processing applications but that it is hard for a newcomer to understand the produced data and properly use a test equipment.

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Camera design publications

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How to extend the operating temperature of FPGAs
Our high temperature camera for oil and gas wells inspection requires to operate at very high temperatures above the specified operating junction temperature of the FPGAs and with limited cooling possibilities. This article published in the Xilinx XCell journal explains how we have achieved this.
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Doppler effect based hyperspectral imaging
There are multiple solutions for hyperspectral imaging, all of them include either grating or filters and therefore lose spatial resolution (2D patterns) or time resolution (1D patterns or line scan or push broom). In this paper, we present a method for hyperspectral imaging that does not require either gratings or multiple filters and that maintains the full 2D resolution of the sensor and arbitrary small wavelength resolution is possible. However, the camera may become heavy.
This paper has been published on April 1st 2017.
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Press releases

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Vision Award 2014 press release
Press release in Industrial Machine Vision Europe (IMVE) about the short listing of Aphesa for the 2014 Vision Award
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About us

Aphesa develops custom cameras and custom electronics including FPGA code and embedded software. We also provide EMVA1288 test equipment and test services as well as consulting and training in machine vision and imaging technologies. Aphesa works in several markets including industrial, medical, oil&gas and security.