Images, WP/CP | Type: PHPSpecify minimum size for image upload

//specify minimum size for uploaded images (including featured images)
add_filter('wp_handle_upload_prefilter','tc_handle_upload_prefilter');
function tc_handle_upload_prefilter($file)
{
    $img=getimagesize($file['tmp_name']);
    $minimum = array('width' => '300', 'height' => '300');
    $width= $img[0];
    $height =$img[1];

    if ($width < $minimum['width'] )
        return array("error"=>"Image dimensions are too small. Minimum width is {$minimum['width']}px. Uploaded image width is $width px");

    elseif ($height <  $minimum['height'])
        return array("error"=>"Image dimensions are too small. Minimum height is {$minimum['height']}px. Uploaded image height is $height px");
    else
        return $file; 
}

Reference Links

https://wordpress.stackexchange.com/questions/28359/how-to-require-a-minimum-image-dimension-for-uploading