gchq/CyberChef · warning · OperationError

Error loading image. (${err})

Error message

Error loading image. (${err})

What it means

Thrown when Jimp.read(input) rejects while loading the image inside Image Brightness/Contrast. This fires only after isImage passed, so the magic bytes looked plausible but the actual decode failed. The original Jimp error is interpolated into the message.

Source

Thrown at src/core/operations/ImageBrightnessContrast.mjs:64

        ];
    }

    /**
     * @param {ArrayBuffer} input
     * @param {Object[]} args
     * @returns {byteArray}
     */
    async run(input, args) {
        const [brightness, contrast] = args;
        if (!isImage(input)) {
            throw new OperationError("Invalid file type.");
        }

        let image;
        try {
            image = await Jimp.read(input);
        } catch (err) {
            throw new OperationError(`Error loading image. (${err})`);
        }
        try {
            if (brightness !== 0) {
                if (isWorkerEnvironment())
                    self.sendStatusMessage("Changing image brightness...");
                image.brightness(brightness / 100);
            }
            if (contrast !== 0) {
                if (isWorkerEnvironment())
                    self.sendStatusMessage("Changing image contrast...");
                image.contrast(contrast / 100);
            }

            let imageBuffer;
            if (image.mime === "image/gif") {
                imageBuffer = await image.getBuffer(JimpMime.png);
            } else {
                imageBuffer = await image.getBuffer(image.mime);

View on GitHub (pinned to 4290ea7539)

Solutions

1. Read the interpolated Jimp error for the specific failure reason.
2. Re-export or re-download the source image to ensure it is complete and uncorrupted.
3. Convert the image to PNG/JPEG with an external tool before invoking.
4. Check the bundled Jimp version supports the image's subformat.

Example fix

// before: feeding a truncated buffer whose header survived but body did not
op.run(truncatedPngBuf, [10, 10]);
// after: feed the complete file
op.run(completePngBuf, [10, 10]);

async function assertJimpReadable(buf) {
  try { await Jimp.read(buf); }
  catch (e) { throw new Error(`Jimp cannot read this image: ${e}`); }
}

try {
  result = await brightness.run(buf, [b, c]);
} catch (e) {
  if (e instanceof OperationError && /Error loading image/.test(e.message)) {
    // re-supply a complete source image
    result = await brightness.run(await reload(fullUrl), [b, c]);
  } else throw e;
}

When it happens

Trigger: Truncated image (magic bytes present but body incomplete); corrupt pixel data; a format Jimp does not support despite a sniffable header (e.g. some WebP/HEIC variants, progressive JPEG edge cases); a buffer that is actually a container (e.g. a SVG with PNG-like bytes).

Common situations: Partial download/capture; conversion artefact from another tool; version mismatch where the bundled Jimp lacks a codec; very large image exceeding Jimp's memory.

Related errors

• Error loading image. (${err})
• Error opening image file. (${err})
• Error loading image. (${err})
• Error opening image. (${err})
• Error normalising image. (${err})

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/97f44a727dd6b064. Report an issue: GitHub.