jpeg2rgb

jpeg2rgb is a simple application to take a JPEG file and decode it into raw RGB pixels and write those pixels to a file. It is meant to be used as a tool to easily generate RGB data when developing applications that operate on raw RGB data.

Currently, it supports writing out to RGB files that use 3 bytes per pixel. The RGB data that is output is prepended with a simple header to assist in reading the data back into a program.

RGB File Data Layout

Each RGB file has a 12 byte header giving some basic metadata that is immediately followed by the actual RGB pixels

Offset	Type	Description
0	uint32_t	Width of the image
4	uint32_t	Height of the image
8	uint8_t	Bytes per pixel
9-11	void	padding
12+	uint8_t[]	RGB data

The total size of the RGB buffer can be derived from the data in the header with the formula (width * height * bpp). The pitch (number of bytes per row) is (width * bpp). Iteration through the data would look like

uint32_t i, j;
for(i = 0; i < height; i++) {
    for(j = 0; j < (width * bpp); j+=3) {
        uint8_t red = buffer[i * j];
        uint8_t blue = buffer[i * j + 1];
        uint8_t green = buffer[i * j + 2];
        // do stuff with the pixel data
    }
}

Building

This project is built using CMake. It does have a dependency on libjpeg-turbo. This can be installed using brew install jpeg-turbo on macOS.

To build, run the following commands:

mkdir build
cd build
cmake ..
make

Usage

Currently, no options are supported. Usage is simply running the command like this:

jpeg2rgb example.jpg example.rgb

License

This software is licensed under the MIT License which a copy has been provided in LICENSE