Read text in image with PHP

Question

I'm trying to read the text from this image:

I want to read the price, e.g. "EUR42721.92"

I tried these libraries:

How to Create a PHP Captcha Decoder with PHP OCR Class: Recognize text & objects in graphical images - PHP Classes
phpOCR: Optical Character Recognizer written in PHP

But they don't work. How can I read the text?

Both script didnt read text and numbers.. Example: EUR42450.92 >> output is like: 787988.. I want like this; free-ocr.com — Bora
tesseract (code.google.com/p/tesseract-ocr) is en opensource OCR library/program. I had pretty decent results with it. — Bart Friederichs
How about saving yourself some effort? stackoverflow.com/questions/4791189/… — cmbuckley
Is it possible that goldprice.org is providing the prices only as graphic files to prevent screen scraping? They might object to you using their data in this way. Do they have any terms+conditions on the site that you would be breaking by doing this? Do they provide an API you could use instead? — SDC

Pedro Amaral Couto Pedro Amaral Couto · Accepted Answer · 2014-10-06T20:07:08

Try this (it worked with me):

$imagick = new Imagick($filePath);

$size = $imagick->getImageGeometry();
$width     = $size['width'];
$height    = $size['height'];
unset($size);

$textBottomPosition = $height-1;
$textRightPosition = $width;

$black = new ImagickPixel('#000000');
$gray  = new ImagickPixel('#C0C0C0');

$textRight  = 0;
$textLeft   = 0;
$textBottom = 0;
$textTop    = $height;

$foundGray = false;

for($x= 0; $x < $width; ++$x) {
    for($y = 0; $y < $height; ++$y) {
        $pixel = $imagick->getImagePixelColor($x, $y);
        $color = $pixel->getColor();
        // remove alpha component
        $pixel->setColor('rgb(' . $color['r'] . ','
                         . $color['g'] . ','
                         . $color['b'] . ')');

        // find the first gray pixel and ignore pixels below the gray
        if( $pixel->isSimilar($gray, .25) ) {
            $foundGray = true;
            break;
        }

        // find the text boundaries 
        if( $foundGray && $pixel->isSimilar($black, .25) ) {
            if( $textLeft === 0 ) {
                $textLeft = $x;
            } else {
                $textRight = $x;
            }

            if( $y < $textTop ) {
                $textTop = $y;
            }

            if( $y > $textBottom ) {
                $textBottom = $y;
            }
        }
    }
}

$textWidth = $textRight - $textLeft;
$textHeight = $textBottom - $textTop;
$imagick->cropImage($textWidth+10, $textHeight+10, $textLeft-5, $textTop-5);
$imagick->scaleImage($textWidth*10, $textHeight*10, true);

$textFilePath = tempnam('/temp', 'text-ocr-') . '.png';
$imagick->writeImage($textFilePath);

$text = str_replace(' ', '', shell_exec('gocr ' . escapeshellarg($textFilePath)));
unlink($textFilePath);
var_dump($text);

You need ImageMagick extension and GOCR installed to run it. If you can't or don't want to install the ImageMagick extension, I'll send you a GD version with a function to calculate colors distances (it's just an extended Pythagorean Theorem).

Don't forget to set the $filePath value.

image parsing for cropping visualization

The image shows that it looks for a gray pixel to change the $foundGray flag. After that, it looks for the first and last pixels from the left and from the top. It crops the image with some padding, the resulting image is resized and it's saved to a temporary file. After that, it's easy to use gocr (or any other OCR command or library). The temporary file can be removed after that.

Read text in image with PHP

2 Answers