🚀 Image Viewer in C

A lightweight, terminal-driven image viewer written in C using the SDL2 graphics library. It reads a PPM (P6 binary) image from stdin and renders it pixel-by-pixel in a native desktop window.

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✨ Features

• Renders PPM (P6 binary format) images using SDL2.
• Pixel-accurate rendering via SDL_FillRect.
• Reads directly from stdin, i.e., no file path argument needed.
• Auto-sizes the window to match the image dimensions.
• Minimal and dependency-light, just C standard library + SDL2.

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🛠 Tech Stack

• Language: C and its Libraries
• Tools: GCC, Neovim, Git, GIMP (To convert files into .ppm format)

📚 Dependencies

Library	Purpose
SDL2	Window creation and pixel rendering
stdio.h	Standard I/O for reading PPM from stdin
stdlib.h	Memory allocation (calloc, free)

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📁 Project Structure

image-viewer/
├── main.c        # Source code
├── images/
    ├── image.ppm     # Sample PPM image (Converted using GIMP)
    └── image.webp    # Original WebP source image

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🚀 Getting Started

To get a copy of this project up and running on their local machine:

Prerequisites

Make sure you have the following installed:

• GCC (or any C compiler)
• SDL2 development libraries

Installation

• Clone the repository:

  git clone https://github.com/vishnuparihar2008/image-viewer.git

• Navigate into the project directory:

  cd ./image-viewer

• Compile the project:

gcc -Wall -Wextra -g -o bin/main main.c `sdl2-config --cflags --libs`

This compiles main.c and links the SDL2 library automatically.

Note

sdl2-config is standard for only Unix-like systems and might not compile on Windows etc.

• Run the project:

cat images/image.ppm | ./bin/main 

Note

cat is standard for only Unix-like systems and might not run on Windows etc.

This runs the viewer by piping a PPM image to the binary
A window will open at the image's native dimensions. Close it by clicking the X button or pressing Alt+F4.

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📄 Expected PPM File Format (P6)

Binary (Raw)

P6
# Optional comment
<width> <height>
255
<binary RGB pixel data...>

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⚙️ How It Works

1. Header Parsing — Reads the PPM header from stdin using fgets to extract image width and height.
2. Window Creation — Creates an SDL2 window sized to the image dimensions.
3. Pixel Rendering — Reads raw RGB bytes pixel-by-pixel using getchar() and fills each 1×1 rectangle on the SDL surface.
4. Display & Event Loop — Calls SDL_UpdateWindowSurface() to show the final image and polls for an SDL_QUIT event to exit.

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💡 Usage Examples

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🗺 Roadmap / Future Enhancements

• Scale it up to preview more than just .ppm files.
• Add a full-scrreen option.
• Implement basic pixel manipulation like:
  • grayscale conversion
  • brightness adjustment

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👩‍💻 Author

Vishnu Parihar — vishnuparihar2008

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📄 License

This project is open source. Feel free to use, modify, and distribute.