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<?php |
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// https://ee-programming-notepad.blogspot.com/2016/09/php-script-to-transform-24-bits-color.html |
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error_reporting(E_ALL); |
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ini_set('display_errors', 'On'); |
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header('Content-type: text/html; charset=utf-8'); |
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set_time_limit(0); |
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// DESCRIPTION: |
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// these functions will transform an 24 bits color depth image file into 16 bits color depth raw file and back again |
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// USEFULNESS: |
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// to be used on the ILI9340 IC based LCD screens (2.2" SPI TFT, 240x320) |
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// NOTES: |
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// - characters representation on 16 bits are made in 2 chars |
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define('IMAGE_WIDTH', 240); |
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define('IMAGE_HEIGHT', 320); |
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function jpeg_image_to_raw_file($filename) |
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{ |
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$im = imagecreatefromjpeg($filename); |
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$output = ''; |
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for ($y = 0; $y < IMAGE_HEIGHT; $y++) |
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{ |
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for ($x = 0; $x < IMAGE_WIDTH; $x++) |
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{ |
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$rgb = imagecolorat($im, $x, $y); |
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// split into color components (RGB) |
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$r = ($rgb >> 16) & 0xFF; |
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$g = ($rgb >> 8) & 0xFF; |
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$b = $rgb & 0xFF; |
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if (1) { |
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// transform into procent of 8-8-8 bits |
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$r_procent = round(($r * 100) / 255); |
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$g_procent = round(($g * 100) / 255); |
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$b_procent = round(($b * 100) / 255); |
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// transform into procent of 5-6-5 bits |
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$r_5bits = round(($r_procent * 31) / 100); |
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$g_6bits = round(($g_procent * 63) / 100); |
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$b_5bits = round(($b_procent * 31) / 100); |
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} else { |
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// loose 3-2-3 bits of color depth |
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$r_5bits = $r >> 3; |
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$g_6bits = $g >> 2; |
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$b_5bits = $b >> 3; |
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} |
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// merge all color components into one |
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$rgb_16bits = ($r_5bits << 11) ^ ($g_6bits << 5) ^ $b_5bits; |
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// split into 2 chunks of 8 bits |
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$char1 = ($rgb_16bits >> 8) & 0xFF; |
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$char2 = $rgb_16bits & 0xFF; |
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// make them ASCII char |
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$rgb_16bits_char = chr($char1) . chr($char2); |
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// join them |
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$output .= $rgb_16bits_char; |
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} |
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} |
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return $output; |
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} |
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function raw_file_to_jpeg_image($filename) |
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{ |
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$content = file_get_contents($filename); |
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$content_len = strlen($content); |
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$im = imagecreatetruecolor(IMAGE_WIDTH, IMAGE_HEIGHT); |
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$increm = 1; |
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$x = 0; |
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$y = 0; |
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for ($i = 0; $i < $content_len; $i += 2) |
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{ |
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// get the first 2 chunks of 8 bits in reversed order and make them numbers again |
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$colors = 0; |
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$k = 1; |
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for ($j = 0; $j < 2; $j++) |
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{ |
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$colors ^= ord($content[$i + $j]) << ($k * 8); |
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$k--; |
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} |
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// split into color components (RGB) |
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$r_5bits_back = ($colors >> 11) & 0x1F; |
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$g_6bits_back = ($colors >> 5) & 0x3F; |
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$b_5bits_back = $colors & 0x1F; |
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// convert from 5-6-5 bits to 8-8-8 bits |
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if (1) { |
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// transform into procent of 5-6-7 bits |
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$r_proc = round(($r_5bits_back * 100) / 31); |
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$g_proc = round(($g_6bits_back * 100) / 63); |
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$b_proc = round(($b_5bits_back * 100) / 31); |
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// transform into 8-8-8 bits of color from procent |
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$r = round(($r_proc * 255) / 100); |
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$g = round(($g_proc * 255) / 100); |
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$b = round(($b_proc * 255) / 100); |
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} else { |
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// add some zeros |
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$r = $r_5bits_back << 3; |
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$g = $g_6bits_back << 2; |
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$b = $b_5bits_back << 3; |
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} |
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// rebuild the image |
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$color = imagecolorallocate($im, $r, $g, $b); |
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imagesetpixel($im, $x, $y, $color); |
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// lets calculate some image coordinates |
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if ($increm % IMAGE_WIDTH == 0) { |
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$y++; |
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$x = 0; |
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} else { |
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$x++; |
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} |
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$increm++; |
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} |
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ob_start(); |
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imagejpeg($im); |
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return ob_get_clean(); |
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} |
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// run the script |
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{ |
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$original_image = 'nature.jpg'; |
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$raw_image = 'nature.raw'; |
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$output_image = 'nature-back.jpg'; |
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echo '<pre>'; |
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if (!file_exists($original_image)) { |
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echo '<b>There is no '.$original_image.' image file</b>'; |
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exit; |
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} |
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// IMAGE TO RAW |
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echo '<b>Transform to raw:</b> <br>'; |
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echo 'input original_image: '.$original_image.'<br>'; |
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echo 'input raw_image: '.$raw_image.'<br>'; |
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file_put_contents($raw_image, jpeg_image_to_raw_file($original_image)); |
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echo 'filesize raw_image: '.filesize($raw_image).'<br>'; |
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// RAW TO IMAGE |
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echo '<br>'; |
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echo '<b>Transform from raw:</b> <br>'; |
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echo 'input raw_image: '.$raw_image.'<br>'; |
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echo 'input output_image: '.$output_image.'<br>'; |
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file_put_contents($output_image, raw_file_to_jpeg_image($raw_image)); |
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} |
