Best way to write an image to a Django HttpResponse()

Well, re-encoding is needed sometimes (i.e. applying an watermark over an image while keeping the original untouched), but for the most simple of cases you can use:

try:
    with open(valid_image, "rb") as f:
        return HttpResponse(f.read(), content_type="image/jpeg")
except IOError:
    red = Image.new('RGBA', (1, 1), (255,0,0,0))
    response = HttpResponse(content_type="image/jpeg")
    red.save(response, "JPEG")
    return response