Semester Project Spring 2025

[mimanerhn]

Student: Imane Raihane
Project Title: An Affordable Development Kit for Lensless Imaging
Semester: Spring 2025
Program: B.Sc. in Computer Science, EPFL

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1. Calibration Box Development : Measuring PSF

To accurately measure the PSF : a point light source is required and must be precisely aligned relative to the sensor. This motivates the need for a stable, reproducible, and adjustable calibration setup.

• Static Calibration Box :

  • Basic and functional : interchangeable aperture sizes and adjustable LED brightness.

  • STL files : STL Files Box.zip

  • 

• X/Y Moving Calibration Box :

  • Precise & accurate PSF alignment, here is the Bill Of Materials (BOM) :

Component	Quantity	Price (CHF)	Webshop / Link
2060 V-Slot Aluminium Extrusion	1	17	Shop
Stepper Motor 28BYJ-48 + Drivers	1	—
M5 Screws	10	1	SPOT EPFL
M3 Screws	10	1	SPOT EPFL
2GT Timing Belts (6 mm width)	2	—	SPOT EPFL
30-Tooth 2GT Pulley	1	—	SPOT EPFL
Linear Rods (8 mm)	2	1.4	SPOT EPFL
Linear Bearings (8 mm)	4	4	SPOT EPFL
Small Idler Pulley (5 mm bore)	2	—	SPOT EPFL
Big Idler Pulley (5 mm bore, 6 mm width)	1	—	SPOT EPFL
Solid V-Wheels	4	12	Shop
Printed Material (custom parts)	–	–	STL Files

Here is the inspiration for Alignment Control Code : Link

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2. Improving the Capture Process : Automatic Determination of Parameters

Auto Exposure

• Automatically select exposure time to avoid under/overexposure

How It Works

In all cases, an initial manual exposure time must be provided : it serves as a starting point for the fine-tuning process. The system will then iteratively adjust until optimal exposure is reached :

For more details about the implementation, here is the PR related to it : #174

To enable automatic exposure adjustment, set the following flags in your command:

• auto_exp_psf = true → when capturing a PSF
• auto_exp_img = true → when capturing a Regular image

PS : By default, both flags are set to false

RGB Gain Correction

To perform color correction, we compute the red and blue gains that align the three RGB channel curves into a single unified curve :

For more details about the implementation, here is the PR related to it : #175

PS : This method is only valid during PSF capture, as it requires a known white object.

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3. Lensless Imaging WebApp

• Repository : Link
• Features:
  • Web interface controls full imaging pipeline
  • Headless operation: only requires browser on same network
  • Step-by-step GUI and online documentation included

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