It's not often I have the same film in multiple formats and editions, so I decided to make a little comparison from still images.
Day of Anger (I Giorni dell'ira, 1967) was directed by Tonino Valerii and it stars Giuliano Gemma and Lee Van Cleef. I tend to think it as an above average spaghetti western, but not outstanding. Admittedly it belongs to an earlier stage of Italian westerns and thus perhaps more innovative than it now seems.
Well, anyway, to the picture quality. I have an italian DVD from "Medusa", which does not have english dubbing or subtitles. So I eventually acquired the Blu-Ray/DVD combo, recently released by Arrow media.
(To see the bigger images properly, you have to click on the images and open them in a new browser window.)
DVD/ Medusa (position 1:03:10)
Even without having anything to compare to, the Medusa DVD does not seem so good. However, the image quality is much better than many cheap spaghetti releases.
DVD/ Arrow (position 1:04:37)
Focusing only on the horses, there seems to be not that much more detail, but then I realized the cropping in the Medusa version :) Overall, the image is of course sharper and the colors are clearer.
Blu-Ray Disc / Arrow
Looking at a still image, the difference between the Blu-Ray and the good DVD is almost as big as between the two DVDs. When watching the moving image, the difference is not that heightened. There's some film grain noise that's not visible in the lower resolution DVD. Note how the color red was a bit blurry in the DVD but not so here.