Using AWS Rekognition to Detect Text in Images with PHP

A couple years ago, I tinkered with a solution to use a webcam to capture images of receipts, covert the images to raw text, and store in a database. My scrappy solution worked okay but it lacked the accuracy to make it viable for anything real-world.

With AWS Rekognition launching since then, I figured I’d try it out and see how it compares. I used a fake receipt to see how it’d do.

Like every other AWS product I’ve used, it was incredibly easy to work it. I’ll share the simple script I used at the bottom of this post but, needless to say, there’s not much to it.

While use was a breeze, the results were disappointing. Primarily, the fact that Rekognition is limited to ONLY 50 words in an image. So clearly it’s not a full-on OCR tool.

Somewhat more disappointing was the limited range of confidence scores Rekognition returned (for each text detection, it provides a confidence score). The overall output was pretty accurate but not accurate enough for me to consider it “wow” worthy. Despite this, all of the confidence scores were above 93%.

To be considered an OCR service, AWS Rekognition has a long way to go before it’s competitive as an OCR service. It’s performance in object detection/facial recognition (which is the heart and primary usecase of Rekognition) may be better but I haven’t tested that at this point.

You can view the full analysis and output of the receipt image here.

Below is the code used to generate the output linked above:

<?php
require '/home/vendor/autoload.php'; 
use Aws\Rekognition\RekognitionClient;

$client = new Aws\Rekognition\RekognitionClient([
    'version'     => 'latest',
    'region'      => 'us-west-2',
    'credentials' => [
        'key'    => 'IAM KEY',
        'secret' => 'IAM SECRET'
    ]
]);

$result = $client->detectText([
    'Image' => [
        'S3Object' => [
            'Bucket' => 'S3 BUCKET CONTAINING IMAGE',
            'Name' => 'receipt_preview.jpg',
        ],
    ],
]);

echo "<h1>Rekognition</h1>";
$i=0;
echo "<table border=1 cellspacing=0><tr><td>#</td><td>DetectedText</td><td>Type</td><td>ID</td><td>ParentId</td><td>Confidence</td></tr>";
foreach ($result['TextDetections'] as $phrase) {
  $i++;
    echo "<tr><td>$i</td><td>".$phrase['DetectedText']."</td><td>".$phrase['Type']."</td><td>".$phrase['Id']."</td><td>".$phrase['ParentId']."</td><td>".round($phrase['Confidence'])."%</td></tr>";
}
echo "</table>";

echo "<h1>Raw Output</h1><pre>";
print_r($result);
echo "</pre>";
?>

 

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