diffimg

diffimg is a command-line tool for comparing two images using the imagediff library's tolerance logic. It supports various image formats and allows for fine-grained control over comparison thresholds via JSON configuration and optional masking.

Usage

bash

diffimg [options] <reference> <candidate>

Arguments

<reference>: Path to the golden/expected image.
<candidate>: Path to the test/actual image.

Options

--config <path>: Path to a JSON configuration file defining comparison thresholds.
--mask <path>: Path to a grayscale mask image (0 = ignore, >0 = compare).
--diff <path>: Path to output a visual difference image (unmasked absolute difference).
--help, -h: Print help message.

Output

The tool outputs a JSON object to stdout containing the comparison results:

json

{
  "status": 0,
  "passed": true,
  "failingPixelCount": 0,
  "maxDiffFound": [0.0, 0.0, 0.0, 0.0]
}

Status Codes

0: PASSED (Images are considered the same within tolerance)
1: SIZE_MISMATCH (Images have different dimensions)
2: PIXEL_DIFFERENCE (Images differ beyond the allowed tolerance)

Configuration Format

The optional JSON configuration follows the imagediff schema:

json

{
    "mode": "LEAF",
    "maxAbsDiff": 0.01,
    "maxFailingPixelsFraction": 0.05
}

Dependencies

libs/imagediff: Comparison logic.
libs/imageio: Primary image decoding (PNG, HDR, EXR).
libs/imageio-lite: Fallback decoding (TIFF).