Gravity forms image size ( width , height ) validation

functions.php

<?php
function limit_file_upload_size( $validation_result ) {

    $images = json_decode(json_decode('"'.$_POST['gform_uploaded_files'].'"', true));

	$form = $validation_result['form'];
	
	foreach( $form['fields'] as &$field ){
		
		$is_hidden = RGFormsModel::is_field_hidden( $form, $field, array() );
		
		if( $is_hidden )
            continue;
            
            
        if($field["id"] == "19")
        {

            foreach($images->input_19 as $image)
            {
                $input_name = 'input_' . $field['id'];
                $temp_location = RGFormsModel::get_upload_path($form['id']) . '/tmp/' . $image->temp_filename;
    
                if ( file_exists( $temp_location ) )
                    $filesize = getimagesize( $temp_location );

                $minimum = array('width' => '768', 'height' => '500');
                $width= $filesize[0];
                $height =$filesize[1];


                if ($width < $minimum['width'] )
                {
                    $validation_result['is_valid'] = false;
                    $field['failed_validation'] = true;
                    $field['validation_message'] = "Image dimensions are too small. Minimum width is {$minimum['width']}px. Uploaded image width is $width px. ( {$image->uploaded_filename} )";
                }
        
                elseif ($height <  $minimum['height'])
                {
                    $validation_result['is_valid'] = false;
                    $field['failed_validation'] = true;
                    $field['validation_message'] = "Image dimensions are too small. Minimum height is {$minimum['height']}px. Uploaded image height is $height px. ( {$image->uploaded_filename} )";
                }
                
            }
        }
    }
    
    $validation_result['form'] = $form;
    return $validation_result;
}
add_filter('gform_validation_1', 'limit_file_upload_size');