Multi-Channel Image Combiner

Build a utility that combines separate grayscale channel images into a single multi-channel RGB or RGBA image.

Requirements

Your solution should:

1. Accept file paths to 3 separate grayscale images representing Red, Green, and Blue channels
2. Optionally accept a 4th grayscale image representing an Alpha channel
3. Combine these separate channel images into a single multi-channel RGB or RGBA output image
4. Validate that all input images have the same dimensions (width and height)
5. Output the combined image to a specified path
6. Support common image formats (PNG, JPEG)

Behavior

• If input images have mismatched dimensions, throw an error with a clear message
• If only RGB channels are provided (no alpha), produce an RGB image
• If RGBA channels are provided (including alpha), produce an RGBA image
• The output format should preserve the channel data accurately

Test Cases

• Combining three 100x100 grayscale images (R, G, B) produces a 100x100 RGB image @test
• Combining four 50x50 grayscale images (R, G, B, A) produces a 50x50 RGBA image @test
• Attempting to combine images with mismatched dimensions throws an error @test

Implementation

@generates

API

/**
 * Combines separate grayscale channel images into a multi-channel image.
 *
 * @param {Object} options - Configuration options
 * @param {string} options.redPath - Path to the red channel image
 * @param {string} options.greenPath - Path to the green channel image
 * @param {string} options.bluePath - Path to the blue channel image
 * @param {string} [options.alphaPath] - Optional path to the alpha channel image
 * @param {string} options.outputPath - Path for the output combined image
 * @returns {Promise<void>}
 * @throws {Error} If input images have mismatched dimensions
 */
async function combineChannels(options) {
  // IMPLEMENTATION HERE
}

module.exports = { combineChannels };

Dependencies { .dependencies }

sharp { .dependency }

Provides image processing capabilities including channel manipulation.