First, you may think these promo images are untouched pictures of the original animation cels. Promo images often look too "clean" and bright compared to the source material. Here are some examples to help differentiate.

These promo images appeared online years after the series aired. They are made to promote the series, serving as advertisements and video thumbnails. Unfortunately, they prioritize being eye catching instead of being accurate, tending to be a bit revisionist.

One common revision we've noticed is that promo images for the original Dragon Ball series tend to make Goku's clothes more orange (or less red). This is likely done to try and fit in with his look in DBZ. You can see how the promo image is a little different from the source.

Some promo images aren't even consistent with each other. In this example from DBZ, Goku's main skin tone has changed from a peachy red to a bright yellow!

Even promo images of the same part of the series lack consistency. Here's a "paint by numbers" example where we swap the colors of two similar promo images. Note that the swaps are not meant to look good, but directly capture the color of the image above.

In addition, some of these promo images are poorly balanced. Black and white things like Goku's hair, eyes, a mask, and clothing appear tinted. Here are what two images look like with a basic balance.

Lastly, these eye catching images are way too bright. In DB, DBZ, and DBGT, the brightest things are ki attacks achieved on film using a technique known as "underlighting". Promo images are already so bright that these effects could no longer stand out as intended.

More on underlighting for anyone curious

While these promo images can be subjectively nice looking, with bold and bright colors certainly appealing to children that Toei hopes to turn into fans, they should clearly be avoided by anyone looking for an accurate reference of Dragon Ball.

What did Seed of Might need to know for our own color correction? You can read more about that here