Pale colors only in exports but fine in viewer

[Mark2Mark]

Hi Rob,

Did you ever experience different colors when exporting?

Here I got
Left: rendered mp4, open in Quicktime (same is in Quicklook)
Middle: rendered frame images, open in Quicklook
Right: Coldtype Viewer

Color is hsl(0.975, 0.99, 0.6), but I see the same happening with other colors.
rendering is the usual release = animation.export("h264", loops=1)

When working with the clips in DaVinci Resolve, their colors look bright as in the viewer, and in the export they become a little pale again.
Maybe there’s a setting I am missing? Did you ever see something like this happening?

[stenson]

I wish I knew! Getting exact colors has always been a mystery to me, and is part of the reason I usually finish my animations in a professional video editor (I've been using Resolve these days, which is known for its color capabilities). That is, I import the exported frames into Resolve as an image sequence, then do any final color manipulation there — so in this case you could re-boost the contrast and even rotate the hue, that kind of thing.

All that said, I'm sure there is some way to get better colors out of both the skia renderer and the ffmpeg mp4 conversion process, it's just a dark art I've never been able to understand.

[Mark2Mark]

But that’s already great to know that you see the same.
In DaVinci the colors look even great when I import and use the videos instead of the single frames. The export gets a bit pale again, but not that much. I’ll keep an eye on it and see if I can find any hints. As a workaround I also thought about color grading in DaVinci, but for now the result was fair enough, had a little retro touch that I didn’t mind :D
Thanks so much for your time and thoughts on this, Rob!

[Mark2Mark]

Maybe this could be related in some way? Could it be that the preview and the render use different color spaces? sRGB vs RGB or such a thing?

[Mark2Mark]

I managed to get an mp4 with way more accurate colors with this ffmpeg command (directly from terminal [without Coldtype]) on a folder of Coldtype generated PNGs:

ffmpeg -framerate 30 -pattern_type glob -i '*.png' -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2,colormatrix=bt601:bt709,format=yuv420p" -c:v libx264 out.mp4

Maybe you could play around with that mouthful a bit and find some useful pieces that can be added to Coldtype.

The visual quality is a little different from the Coldtype mp4s (looks more artificially sharpened).

[Mark2Mark]

So I ended up using this as a custom release funtion:

def release(passes):
    from coldtype.osutil import show_in_finder
    from subprocess import run

    animations = set([p.render for p in passes])

    for a in animations:
        root = a.pass_path(f"%4d.{a.fmt}").parent.parent
        mp4 = root / (a.name + ".mp4")
        frames = str(root / a.name / '*.png')
        run([
            "ffmpeg",
            "-y", # overwrite existing files
            "-loglevel", "16", # 'error, 16' Show all errors
            "-framerate", str(a.timeline.fps),
            "-pattern_type", "glob",
            "-i", frames,
            "-vf", "scale=trunc(iw/2)*2:trunc(ih/2)*2",
            "-vf", "colormatrix=bt601:bt709",
            "-pix_fmt", "yuv420p", # pixel format
            "-c:v", "libx264",
            # "-crf", "18", # Not required for this custom wrapper. almost doubles the file size with no visual difference
            mp4
            ])
        print("\n")
        
        show_in_finder(mp4.parent)

It is based on your custom gifsky wrapper, you showed me, but instead using this ffmpeg command.

---

Here is an example:

top = Coldtype Viewer
middle = this custom renderer [73kb]
bottom = default Coltype ffmpeg render (h264) [91kb]

While the custom one is still not perfectly bright, it is definitely closer to the targeted color, and when used on my website it visually blends quite well into my color scheme of the site.

[stenson]

all looks good to me! I do wish I had a better answer to the color issue, though I think the place to "fix" it would be the PNG export, not the mp4 command, so I don't think it'd make sense to incorporate the colormatrix changes in Coldtype directly, at least not until the png color space issue is fixed (though I have no idea how to fix that). All in all, I tend to think of the colors that come out of Coldtype as a starting point for my own work, and I often end up tweaking them in another app before creating any final assets. Definitely room for improvement, and great to have your solution here as a reference for others!

[Mark2Mark]

Maybe I forgot to mention it, but the colors of the PNGs are perfectly fine.

All in all, I tend to think of the colors that come out of Coldtype as a starting point for my own work, and I often end up tweaking them in another app before creating any final assets

Tweaking the colors afterwards is not such a nice option for me. First, it is against one of my main benefits of Coldtype: automated generation of images/animations. Secondly, it is not only cumbersome to import images into another app, and especially get the colors right to the value there. I mean, if I got a pale green, how can I get that back to exactly the one I intended with tweaking color filters?

Anyway, This custom method works better for me, and I might try if I can get it even better.

though I think the place to "fix" it would be the PNG

Hm, I really think ffmpeg and its settings are to blame here, as the PNGs are perfect, and also my different settings show different results.

great to have your solution here as a reference for others!

Yes, anyone, be my guest :)