Artifacts in dark areas?

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Joined: Sun Jun 09, 2019 2:59 pm

Artifacts in dark areas?

Post by Hyeronimous »


First of all, thanks for this wonderful software.

I am quite new to making dcps and here is a problem I haven't been able to figure out.

I am making a dcp from an mp4 file of an animated movie. The original file is high quality and looks perfectly fine, but when I make a dcp and watch it on the player some strange things happen.

Every time there is a fade from black, artifacts and colour shifts appear. Sometimes the artifacts are grid-like forming repeating square-ish patterns. This only happens briefly in the darkest colours of the image, during the moments when the image is coming to life from black. After that, colours are perfectly normal.

Also, in some dark areas of regular images, like for instance the hair of a character, a similar thing happens: some colours appear to be shifted in the dark areas an what looks like compression artifacts appear.

I have tried several settings and gamma values with varying degrees of success. Maximizing the bitrate helped quite a bit, but nothing I did really solved the problem.

However, and here comes a strange twist, when I capture screenshots of the same problematic frame from both the mp4 file in Premiere and the dcp in the player, the images captured look darker and perfectly fine in photoshop and even in windows explorer. It takes changing the gamma point with the levels tool in photoshop to about 2.2 to get something similar to what I actually see in the screen of the player. Now I don't know why this happens but the problematic frames are much less problematic in the screenshot, even if they are, supposedly, the same image. ???

Now, does that mean what I am seeing is just what happens in the dark areas that projectors don't reproduce anyway or is this a real problem? Could this be an issue with the adjustments on my player? Any ideas of what is happening?

I attach some images. Even though the problem might seem subtle in the pictures it is quite disturbing when seen in the player. Notice the colour shift in the hair and underneath the star. Can anyone help me to solve the mystery?

Thanks and best regards!
combo02.jpg (560.39 KiB) Viewed 14602 times
combo01.jpg (380.42 KiB) Viewed 14602 times
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