wp_read_image_metadata( string $file )

function wp_read_image_metadata( $file ) {
	if ( ! file_exists( $file ) )
		return false;

	list( , , $sourceImageType ) = @getimagesize( $file );

	/*
	 * EXIF contains a bunch of data we'll probably never need formatted in ways
	 * that are difficult to use. We'll normalize it and just extract the fields
	 * that are likely to be useful. Fractions and numbers are converted to
	 * floats, dates to unix timestamps, and everything else to strings.
	 */
	$meta = array(
		'aperture' => 0,
		'credit' => '',
		'camera' => '',
		'caption' => '',
		'created_timestamp' => 0,
		'copyright' => '',
		'focal_length' => 0,
		'iso' => 0,
		'shutter_speed' => 0,
		'title' => '',
		'orientation' => 0,
		'keywords' => array(),
	);

	$iptc = array();
	/*
	 * Read IPTC first, since it might contain data not available in exif such
	 * as caption, description etc.
	 */
	if ( is_callable( 'iptcparse' ) ) {
		@getimagesize( $file, $info );

		if ( ! empty( $info['APP13'] ) ) {
			$iptc = @iptcparse( $info['APP13'] );

			// Headline, "A brief synopsis of the caption."
			if ( ! empty( $iptc['2#105'][0] ) ) {
				$meta['title'] = trim( $iptc['2#105'][0] );
			/*
			 * Title, "Many use the Title field to store the filename of the image,
			 * though the field may be used in many ways."
			 */
			} elseif ( ! empty( $iptc['2#005'][0] ) ) {
				$meta['title'] = trim( $iptc['2#005'][0] );
			}

			if ( ! empty( $iptc['2#120'][0] ) ) { // description / legacy caption
				$caption = trim( $iptc['2#120'][0] );

				mbstring_binary_safe_encoding();
				$caption_length = strlen( $caption );
				reset_mbstring_encoding();

				if ( empty( $meta['title'] ) && $caption_length < 80 ) {
					// Assume the title is stored in 2:120 if it's short.
					$meta['title'] = $caption;
				}

				$meta['caption'] = $caption;
			}

			if ( ! empty( $iptc['2#110'][0] ) ) // credit
				$meta['credit'] = trim( $iptc['2#110'][0] );
			elseif ( ! empty( $iptc['2#080'][0] ) ) // creator / legacy byline
				$meta['credit'] = trim( $iptc['2#080'][0] );

			if ( ! empty( $iptc['2#055'][0] ) && ! empty( $iptc['2#060'][0] ) ) // created date and time
				$meta['created_timestamp'] = strtotime( $iptc['2#055'][0] . ' ' . $iptc['2#060'][0] );

			if ( ! empty( $iptc['2#116'][0] ) ) // copyright
				$meta['copyright'] = trim( $iptc['2#116'][0] );

			if ( ! empty( $iptc['2#025'][0] ) ) { // keywords array
				$meta['keywords'] = array_values( $iptc['2#025'] );
			}
		 }
	}

	/**
	 * Filters the image types to check for exif data.
	 *
	 * @since WP-2.5.0
	 *
	 * @param array $image_types Image types to check for exif data.
	 */
	if ( is_callable( 'exif_read_data' ) && in_array( $sourceImageType, apply_filters( 'wp_read_image_metadata_types', array( IMAGETYPE_JPEG, IMAGETYPE_TIFF_II, IMAGETYPE_TIFF_MM ) ) ) ) {
		$exif = @exif_read_data( $file );

		if ( ! empty( $exif['ImageDescription'] ) ) {
			mbstring_binary_safe_encoding();
			$description_length = strlen( $exif['ImageDescription'] );
			reset_mbstring_encoding();

			if ( empty( $meta['title'] ) && $description_length < 80 ) {
				// Assume the title is stored in ImageDescription
				$meta['title'] = trim( $exif['ImageDescription'] );
			}

			if ( empty( $meta['caption'] ) && ! empty( $exif['COMPUTED']['UserComment'] ) ) {
				$meta['caption'] = trim( $exif['COMPUTED']['UserComment'] );
			}

			if ( empty( $meta['caption'] ) ) {
				$meta['caption'] = trim( $exif['ImageDescription'] );
			}
		} elseif ( empty( $meta['caption'] ) && ! empty( $exif['Comments'] ) ) {
			$meta['caption'] = trim( $exif['Comments'] );
		}

		if ( empty( $meta['credit'] ) ) {
			if ( ! empty( $exif['Artist'] ) ) {
				$meta['credit'] = trim( $exif['Artist'] );
			} elseif ( ! empty($exif['Author'] ) ) {
				$meta['credit'] = trim( $exif['Author'] );
			}
		}

		if ( empty( $meta['copyright'] ) && ! empty( $exif['Copyright'] ) ) {
			$meta['copyright'] = trim( $exif['Copyright'] );
		}
		if ( ! empty( $exif['FNumber'] ) ) {
			$meta['aperture'] = round( wp_exif_frac2dec( $exif['FNumber'] ), 2 );
		}
		if ( ! empty( $exif['Model'] ) ) {
			$meta['camera'] = trim( $exif['Model'] );
		}
		if ( empty( $meta['created_timestamp'] ) && ! empty( $exif['DateTimeDigitized'] ) ) {
			$meta['created_timestamp'] = wp_exif_date2ts( $exif['DateTimeDigitized'] );
		}
		if ( ! empty( $exif['FocalLength'] ) ) {
			$meta['focal_length'] = (string) wp_exif_frac2dec( $exif['FocalLength'] );
		}
		if ( ! empty( $exif['ISOSpeedRatings'] ) ) {
			$meta['iso'] = is_array( $exif['ISOSpeedRatings'] ) ? reset( $exif['ISOSpeedRatings'] ) : $exif['ISOSpeedRatings'];
			$meta['iso'] = trim( $meta['iso'] );
		}
		if ( ! empty( $exif['ExposureTime'] ) ) {
			$meta['shutter_speed'] = (string) wp_exif_frac2dec( $exif['ExposureTime'] );
		}
		if ( ! empty( $exif['Orientation'] ) ) {
			$meta['orientation'] = $exif['Orientation'];
		}
	}

	foreach ( array( 'title', 'caption', 'credit', 'copyright', 'camera', 'iso' ) as $key ) {
		if ( $meta[ $key ] && ! seems_utf8( $meta[ $key ] ) ) {
			$meta[ $key ] = utf8_encode( $meta[ $key ] );
		}
	}

	foreach ( $meta['keywords'] as $key => $keyword ) {
		if ( ! seems_utf8( $keyword ) ) {
			$meta['keywords'][ $key ] = utf8_encode( $keyword );
		}
	}

	$meta = wp_kses_post_deep( $meta );

	/**
	 * Filters the array of meta data read from an image's exif data.
	 *
	 * @since WP-2.5.0
	 * @since WP-4.4.0 The `$iptc` parameter was added.
	 *
	 * @param array  $meta            Image meta data.
	 * @param string $file            Path to image file.
	 * @param int    $sourceImageType Type of image.
	 * @param array  $iptc            IPTC data.
	 */
	return apply_filters( 'wp_read_image_metadata', $meta, $file, $sourceImageType, $iptc );

}