memories/lib/ClustersBackend/PeopleBackendUtils.php

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<?php
declare(strict_types=1);
/**
* @copyright Copyright (c) 2023 Varun Patil <radialapps@gmail.com>
* @author Varun Patil <radialapps@gmail.com>
* @license AGPL-3.0-or-later
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
namespace OCA\Memories\ClustersBackend;
trait PeopleBackendUtils
{
/**
* Sort a list of faces by the score.
*
* Needs the following fields:
* - x: x position of the face in the image (percentage)
* - y: y position of the face in the image (percentage)
* - width: width of the face in the image (percentage)
* - height: height of the face in the image (percentage)
* - image_width: width of the image in pixels
* - image_height: height of the image in pixels
* - fileid: file id of the image (unused, converted to int)
*
* A score is calculated for each face, and the list is sorted by that score.
*/
private function sortByScores(array &$list): void
{
// Score the face detections
foreach ($list as &$p) {
// Make sure we have integers
$p['fileid'] = (int) $p['fileid'];
// Get actual pixel size of face
$iw = min((int) ($p['image_width'] ?: 512), 2048);
$ih = min((int) ($p['image_height'] ?: 512), 2048);
$w = (float) $p['width'];
$h = (float) $p['height'];
// Get center of face
$x = (float) $p['x'] + (float) $p['width'] / 2;
$y = (float) $p['y'] + (float) $p['height'] / 2;
// 3D normal distribution - if the face is closer to the center, it's better
$positionScore = exp(-($x - 0.5) ** 2 * 4) * exp(-($y - 0.5) ** 2 * 4);
// Root size distribution - if the image is bigger, it's better,
// but it doesn't matter beyond a certain point
$imgSizeScore = ($iw * 100) ** (1 / 2) * ($ih * 100) ** (1 / 2);
// Faces occupying too much of the image don't look particularly good
$faceSizeScore = (-$w ** 2 + $w) * (-$h ** 2 + $h);
// Combine scores
$p['score'] = $positionScore * $imgSizeScore * $faceSizeScore;
}
// Sort previews by score descending
usort($list, fn ($a, $b) => $b['score'] <=> $a['score']);
}
/**
* Crop the preview to the face.
*
* Needs the following fields:
* - x: x position of the face in the image (percentage)
* - y: y position of the face in the image (percentage)
* - width: width of the face in the image (percentage)
* - height: height of the face in the image (percentage)
*
* @param \OCP\Files\SimpleFS\ISimpleFile $file Actual file containing the image
* @param array $object The face object
* @param float $padding The padding to add around the face
*
* @return [Blob, mimetype] of resulting image
*
* @throws \Exception if file could not be used
*/
private function cropFace($file, array $photo, float $padding)
{
$img = new \OCP\Image();
$img->loadFromData($file->getContent());
$iw = $img->width();
$ih = $img->height();
if ($iw <= 0 || $ih <= 0) {
throw new \Exception('Invalid image size');
}
// Get target dimensions
$dw = (float) $photo['width'];
$dh = (float) $photo['height'];
$dcx = (float) $photo['x'] + (float) $photo['width'] / 2;
$dcy = (float) $photo['y'] + (float) $photo['height'] / 2;
$faceDim = max($dw * $iw, $dh * $ih) * $padding;
// Crop image
$img->crop(
(int) ($dcx * $iw - $faceDim / 2),
(int) ($dcy * $ih - $faceDim / 2),
(int) $faceDim,
(int) $faceDim
);
// Max 512x512
$img->scaleDownToFit(512, 512);
return [$img->data(), $img->mimeType()];
}
}