PHP 图像处理识别答题卡：提取题目答案和特征

// Step 2: Convert the image to a grayscale imagefilter($image, IMG_FILTER_GRAYSCALE);

// Step 3: Threshold the image imagefilter($image, IMG_FILTER_CONTRAST, -255);

// Step 4: Convert the image to binary $threshold = 50;

for($x=0;$x<imagesx($image);$x++) { for($y=0;$y<imagesy($image);$y++) { $rgb = imagecolorat($image,$x,$y); $r = ($rgb >> 16) & 0xFF; $g = ($rgb >> 8) & 0xFF; $b = $rgb & 0xFF;

    $gray = (int)($r+$g+$b)/3;

    if($gray>$threshold)
        $gray = 255;
    else
        $gray = 0;

    $new_pxl = imagecolorallocate($image,$gray,$gray,$gray);
    imagesetpixel($image,$x,$y,$new_pxl);
}

}

// Step 5: Detect edges $new_image = imagecreatetruecolor(imagesx($image), imagesy($image));

for($x=1;$x<imagesx($image)-1;$x++){ for($y=1;$y<imagesy($image)-1;$y++){ $rgb_array = array();

    $rgb_array[] = imagecolorat($image,$x-1,$y-1);
    $rgb_array[] = imagecolorat($image,$x-1,$y);
    $rgb_array[] = imagecolorat($image,$x-1,$y+1);
    $rgb_array[] = imagecolorat($image,$x,$y-1);
    $rgb_array[] = imagecolorat($image,$x,$y);
    $rgb_array[] = imagecolorat($image,$x,$y+1);
    $rgb_array[] = imagecolorat($image,$x+1,$y-1);
    $rgb_array[] = imagecolorat($image,$x+1,$y);
    $rgb_array[] = imagecolorat($image,$x+1,$y+1);

    $r_sum = 0;
    $g_sum = 0;
    $b_sum = 0;

    foreach($rgb_array as $rgb){
        $r = ($rgb >> 16) & 0xFF;
        $g = ($rgb >> 8) & 0xFF;
        $b = $rgb & 0xFF;

        $r_sum += $r;
        $g_sum += $g;
        $b_sum += $b;
    }

    $r = (int)($r_sum/9);
    $g = (int)($g_sum/9);
    $b = (int)($b_sum/9);

    $new_pxl = imagecolorallocate($new_image,$r,$g,$b);
    imagesetpixel($new_image,$x,$y,$new_pxl);
}

}

// Step 6: Detect lines $lines = array();

for($x=0;$x<imagesx($new_image);$x++){ $rgb_array = array();

for($y=1;$y<imagesy($new_image);$y++){
    $rgb_array[] = imagecolorat($new_image,$x,$y);
}

$r_sum = 0;
$g_sum = 0;
$b_sum = 0;

foreach($rgb_array as $rgb){
    $r = ($rgb >> 16) & 0xFF;
    $g = ($rgb >> 8) & 0xFF;
    $b = $rgb & 0xFF;

    $r_sum += $r;
    $g_sum += $g;
    $b_sum += $b;
}

$r = (int)($r_sum/(imagesy($new_image)-1));
$g = (int)($g_sum/(imagesy($new_image)-1));
$b = (int)($b_sum/(imagesy($new_image)-1));

if($r+$g+$b<717){
    $lines[] = $x;
}

}

// Step 7: Extract questions and answers $questions = array(); $answers = array();

$start_line = 0;

foreach($lines as $line){ if($start_line == 0) $start_line = $line; else{ $width = $line-$start_line; $question = imagecreatetruecolor($width, imagesy($image)); imagecopy($question, $image, 0, 0, $start_line, 0, $width, imagesy($image));

    // Step 8: Extract features
    $black_pixels = 0;

    for($x=0;$x<imagesx($question);$x++){
        for($y=0;$y<imagesy($question);$y++){
            $rgb = imagecolorat($question,$x,$y);
            $r = ($rgb >> 16) & 0xFF;
            $g = ($rgb >> 8) & 0xFF;
            $b = $rgb & 0xFF;

            if($r+$g+$b<765)
                $black_pixels++;
        }
    }

    // Step 9: Classify question and answer
    if($black_pixels<=100)
        $answers[] = $question;
    else
        $questions[] = $question;

    $start_line = $line;
}

}

// Step 10: Display the results echo 'Questions:'; foreach($questions as $question) imagejpeg($question, 'question.jpg');

echo 'Answers:'; foreach($answers as $answer) imagejpeg($answer, 'answer.jpg');