python – 测试一个Django站点显示正确的图形 – 图像相似性？

home.html的

<img id="id_graph_image" src="/graphs/selected_graph.png">

图/ urls.py

urlpatterns = patterns('',# other patterns...
        url(r'^graphs/selected_graph.png$','graphs.views.show_selected_graph'),)

图/ views.py

def show_selected_graph(request):
    # matplotlib code...
    canvas = FigureCanvasAgg(figure)
    response = HttpResponse(content_type='image/png')
    canvas.print_png(response)
    return response

图/ tests.py

def test_selected_graph_shows_the_right_graphs(self):
    # request and response...
    graph_on_page = Image.open(StringIO(response.content)).
    expected_graph = Image.open('file://../graphs/static/scenario_1_statistic_1.png')
    # TODO: compare graphs

我想添加Selenium测试或单元测试以确认图形视图返回给定数据集的正确图像.我已经尝试将两个图像与PIL和直方图的RMS差异进行比较,但任何两个matplotlib图形图像都具有相似的直方图.

“百分比差异”是否简单？我应该以一种非常不同的方式测试吗？

我感谢任何和所有的帮助,谢谢！