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What I would like to do is, using the Image field in core, to restrict uploaded images not just on resolution, but also on aspect ratio.

In other words, the image must be 2:3 width to height, and at least 200 by 300 pixels.

I know that Image Styles can manipulate the way an image is viewed. I'm not interested in that. Rather, I want to restrict uploads the same way that you can currently set min/max settings for resolution, I want to add aspect ratio.

My guess is that I'll need to write my own module to add a new check to Image's checks, but perhaps you know of a simpler way.

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I'm not aware of such module either. Upvoted. – AyeshK Nov 15 '12 at 3:02
up vote 7 down vote accepted

My advice would be to implement a custom file validator.

To see how these are used when saving files, you can check out file_save_upload. For an example implementation that is very close to what you want to achieve, check out file_validate_image_resolution.

My super quick attempt at this

 * Validates an image upload as having a particular aspect ratio
 * @param $file
 *   - the uploaded file
 * @param $aspect_ratio
 *   - the apect ratio in the format [WIDTH]:[HEIGHT]. E.g. '3:2'
function file_validate_image_aspect(stdClass $file, $aspect_ratio = 0) {
  $errors = array();

  // Check first that the file is an image.
  if ($info = image_get_info($file->uri)) {
    if ($aspect_ratio) {
      // Check that it is smaller than the given dimensions.
      list($width, $height) = explode(':', $aspect_ratio);
      if ($width * $info['height'] != $height * $info['width']) {
        $errors[] = t('The image is the wrong aspect ratio; the aspect ratio needed is %ratio.', array('%ratio' => $aspect_ratio));

  return $errors;
share|improve this answer
Supremely helpful. This was the pointer in the direction I was looking for. I am going to give it a shot. Tons of thanks. – ezrock Nov 16 '12 at 14:59
I looked around, and I was confused as to why file_validate_image_resolution always returned an array, even if there were no errors. Then I found the discussion of file_validate which I am linking to here for anyone else. – ezrock Nov 16 '12 at 15:08

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