What causes "Failed to read pixel color at position " in Intervention/image?

Reject or clamp negative coordinates before calling colorAt() — they pass the library's check but are invalid for Imagick.

Intervention/image · error · Intervention\Image\Exceptions\AnalyzerException

Failed to read pixel color at position

Error message

Failed to read pixel color at position

What it means

After passing the library's upper-bound check, Imagick's getImagePixelColor($x, $y) itself threw and was wrapped as AnalyzerException. Because the validation in analyze() only rejects x > width-1 / y > height-1, negative coordinates sail through and make Imagick fail inside colorAt(); the remaining cause is a damaged frame resource.

Source

Thrown at src/Drivers/Imagick/Analyzers/PixelColorAnalyzer.php:48

            );
        }

        $colorProcessor = $this->driver()->colorProcessor($image);

        return $this->colorAt($colorProcessor, $image->core()->frame($this->frame));
    }

    /**
     * @throws AnalyzerException
     */
    protected function colorAt(ColorProcessorInterface $processor, FrameInterface $frame): ColorInterface
    {
        try {
            return $processor->import(
                $frame->native()->getImagePixelColor($this->x, $this->y),
            );
        } catch (ImagickException $e) {
            throw new AnalyzerException(
                'Failed to read pixel color at position ' . $this->x . ', ' . $this->y,
                previous: $e,
            );
        }
    }
}

View on GitHub (pinned to 5598b9e397)

Solutions

Reject or clamp negative coordinates before calling colorAt() — they pass the library's check but are invalid for Imagick.
If coordinates are already non-negative, re-read the image from the original bytes and retry once; persistent failure indicates a corrupt file.

Example fix

// before
$color = $image->colorAt($x - 1, $y); // $x == 0 makes this -1

// after
$left = max(0, $x - 1);
$color = $image->colorAt($left, $y);

Defensive patterns

Strategy: validation

Validate before calling

// the library only guards the upper bound; negatives must be checked by the caller
if ($x < 0 || $y < 0 || $x >= $image->width() || $y >= $image->height()) {
    throw new \InvalidArgumentException("Pixel ($x, $y) is outside the image");
}
$color = $image->colorAt($x, $y);

Type guard

function isValidPixel(\Intervention\Image\Interfaces\ImageInterface $image, int $x, int $y): bool
{
    return $x >= 0 && $y >= 0 && $x < $image->width() && $y < $image->height();
}

Try / catch

try { $color = $image->colorAt($x, $y); } catch (AnalyzerException $e) { /* coordinates already validated → suspect corrupt frame: re-read from bytes */ }

Prevention

Watch neighbor lookups at edges: $x - 1 at x=0 is -1 and passes the library check.
Use max(0, ...) around modulo/wrapping index math.
Reject negative coordinates from user input or templates.

When it happens

Trigger: colorAt(-1, 0) or colorAt(0, -5) — negative indices from modulo/wrapping math, signed arithmetic, or sentinel defaults like -1; reading a pixel from a frame whose Imagick internal state is corrupted.

Common situations: Tiling/wrapping code using (($i - 1) % $width); coordinates parsed from user input or template variables that permit negatives; neighbor-pixel lookups at x=0/y=0 edges.

Related errors

AI-assisted analysis of Intervention/image@5598b9e397 (2026-08-23). Data as JSON: /api/errors/b086effdaaf863aa. Report an issue: GitHub.