public static function GdImageAnalysis::mean in Image Effects 8.3

Same name and namespace in other branches

1. 8 src/Component/GdImageAnalysis.php \Drupal\image_effects\Component\GdImageAnalysis::mean()
2. 8.2 src/Component/GdImageAnalysis.php \Drupal\image_effects\Component\GdImageAnalysis::mean()

Calculates the mean pixel intensity.

Parameters

resource $image: A GD image resource.

Return value

float The mean pixel intensity value.

4 calls to GdImageAnalysis::mean()

GdImageAnalysisTest::testDifference in tests/src/Unit/GdImageAnalysisTest.php

Verify the difference calculation.

GdImageAnalysisTest::testMean in tests/src/Unit/GdImageAnalysisTest.php

Verify the mean calculation with a known image.

ImageEffectsTestBase::assertImagesAreEqual in tests/src/Functional/ImageEffectsTestBase.php

Asserts that two GD images are equal.

ImageEffectsTestBase::assertImagesAreNotEqual in tests/src/Functional/ImageEffectsTestBase.php

Asserts that two GD images are not equal.

File

src/Component/GdImageAnalysis.php, line 19

Class

GdImageAnalysis

Image analysis helper methods for GD.

Namespace

Drupal\image_effects\Component

Code

public static function mean($image) {
  $mean = 0;
  $size = imagesx($image) * imagesy($image) * 3;
  for ($i = 0; $i < imagesx($image); $i++) {
    for ($j = 0; $j < imagesy($image); $j++) {
      $rgb = imagecolorat($image, $i, $j);
      $r = $rgb >> 16 & 0xff;
      $g = $rgb >> 8 & 0xff;
      $b = $rgb & 0xff;
      $mean += $r / $size;
      $mean += $g / $size;
      $mean += $b / $size;
    }
  }
  return $mean;
}