How could I make hitbox visualization images for bullets?

[LudicrousFPS]

I'm thinking about making images that show the actual hitboxes for every single unique piece of danmaku. I already have the values of size, but I don't really know how to count pixels and create the visuals. Ideally I want something like the attachment.

[JustATypicalReisenFan]

if you have the sizes, then you could probably grab the bullet sprites off of spriter's resource and use a pixel art editor
i think

[degradingwindow]

Just like what JustATypicalReisenFan said:

You can probably find a dump of all the bullet sprites for all the Touhou games online somewhere.

Because you're going to be making an image, i recommend using an image editor rather than a pixel one though.

99% of Image Manipulation Programs have a ruler which you can use to easily measure the pixels of the sprites and then you can draw in a circle or a square with their perspective tools.

If you want, you can even use MS Paint to do it. Just load up the pictures, measure them and then draw the hitboxes over them with the square or circle tools. But if you want a clean and good looking picture, I recommend learning how to use GIMP or Photoshop. If you have any other questions, id be glad to answer them.