Kr3b5 / scanEnhancer

Study project at FSU Jena for improving the quality of scanned documents

Enhancer for Scanned Images

Algorithm Engineering
Friedrich Schiller University Jena
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About The Project

Free tool (executable) for improving the quality of scanned documents before printing (or sending) them.

• Input: portable pix map (ppm) color image(s) in ASCII-format (P3)
  • Tool to convert image to P3 ppm image: IrfanView
    • ⚠️ IrfanView writes a comment in the image which must be deleted with a texteditor:

    P3
    # Created by IrfanView   <-- delete this line and save file 
    1440 809
    

• Output: cleaned ppm image(s) in ASCII-format

Built With

• C++
• CMake

📚 Libraries

• OpenMP
• Catch2

Getting Started (Linux)

🔨 Build project

To compile the project a c++ compiler and cmake is needed. If it is missing execute the following commands:

sudo apt update 
sudo apt install cmake 
sudo apt install gcc  

Next, the project must be copied locally:

git clone https://github.com/Kr3b5/fsu-algoeng.git

Now you can go into the project directory and start the build:

cmake -B build
cmake --build build

⚠️ if you get the error No CMAKE_CXX_COMPILER could be found run the following command:

export CXX=[path to g++]/g++ (default: /usr/bin/g++)

✅ If the build was successful, the executable file can be found under project/build/scanEnhancer

ℹ️ Test project

To test the project the following commands can be used:

catch2 (more detailed):

cd /project/build
./scanEnhancer_tests

ctest:

cd /project/build
ctest

Usage

usage: scanEnhancer <path input file> <path output file> [filters]
  filter (needs at least one filter):
    -g <radius>                    apply gauss filter with radius
    -t <radius> <C> <text mode>    apply mean threshold filter with radius and offset C
           > text mode = [0 = off | 1 = on] 

• -g - Gaussian filter to reduce noise, but blurrs the image
• -t - Mean threshold to remove background and shadows in text images
  • ℹ️ text mode = Colors all pixels that are not removed black for better readability

Example for img/in.ppm:

./scanEnhancer ../img/in.ppm ../img/out.ppm -g 3 -t 10 5 1

Input	Output	Output - Textmode

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