Laravel - Input field for image URL

i want to save image URL in database. I have migration

public function up()
{
    Schema::table('posts', function (Blueprint $table) {
        $table->binary('image')->nullable();
    });
}

/**
 * Reverse the migrations.
 *
 * @return void
 */
public function down()
{
    Schema::table('posts', function (Blueprint $table) {
        $table->dropColumn('image');
    });
}

}

in my view i have input field

<div class="form-group">
                                <label for="imageUrl">Image URL</label>
                                <input type="text" class="form-control" id="image" name="image" placeholder="Image url">
                            </div>

In my controller i have this code>

public function store(Request $request){

    $post = Post::create($request->all());
    $title = $post->title;
    $id = 0;
    $slug = str_slug($title);

    $allSlugs = $this->getRelatedSlugs($slug, $id);

    if (!$allSlugs->contains('slug', $slug)){
        $post->slug = $slug;
    }
    else{
        for ($i = 1; $i <= 10; $i++) {
            $newSlug = $slug.'-'.$i;
            if (!$allSlugs->contains('slug', $newSlug)) {
                $post->slug = $newSlug;
            }
        }
    }
    $post->save();

    return redirect('/home');

When i add image url in input field in the database image field is always null. How i can add image url in database?

via Chebli Mohamed