Sharing my new findings on color sources. I have been looking for Dragon Ball cel for the past month, however I think I'm 15 years late to this because the price is beyond ridiculous now. Any random cel costed at least $200 and any cel with Goku easily exceeded $1,000.
I did grab a few 30 cels from other animations for cheap, though not DBZ, they still share some common cel color characteristics that are worth noting, such as the range from black to white. The darkest black I have seen from my scans is RGB(23, 26, 26), typically they are at around RGB(30, 30, 30). The white paint on the cels are around RGB(250, 247, 237), with the red value always be the highest and the blue the lowest. And there is no white that is in the 250s.
I also compared my color accurate scan to the one taken from iphone, such as this:
As expected, the color by the phone is way off. This is a prove of my assumption that cel taken by phone under insufficient light source (99.99% of the time) is inaccurate and cannot be use as color reference.
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Beside getting on hand with the actual cel, I have found another way that may be the color source we need. I had came into
this blog post about a trip to the Sekaido store in Tokyo, and this store happens to be selling cel paint produced by Toei Animation, all with number labeled. Now I'm not sure if the color label is matching to the one on dbz cel sketches since we only have one photo of it. But if they do, this is going to be a game changer. And the cost for those all the cel paints is probably be less than the cost of one Goku cel. This is still a long shot though since we'll need to have someone actually going there to confirm it first.
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I also tried the approach on getting color from the dbz carddass. The vibrant color is pretty good and looks right, however the darker color is very inconsistent, sometime blueish sometime greenish. I'm suspecting this to be caused by the screen printed on the cards and I still couldn't figure out a way to fix it. See in this example, all the color looks right except for Goku's black hair:
