Color Remap: Quick and dirty way to change color for doom graphics

Have you ever seen a wall in doom and thought "This wall is great, but I wish it was different color"? Or perhaps have you ever seen a baron of hell and thought "I love barons of hell, but I wish they were green"? SLADE3, the most common program for editing doom resources has a tool just for that. It's called "Color Remap".

For this guide, we will give a baron of hell green skin and yellow glow around his fists. But it can also be used for wall textures and flats.

First of all, let's separate graphic we need changed. Like this baron, the BOSS family of sprites. I will not cover proper ways to handle Doom graphics, only this specific tool. Look up guides for that if you need to. Note, that the graphic needs to be paletted (Be Graphic (Doom) or Flat (Doom)) - some ports can work with PNG, but the tool will not.

The remap tool can be accessed through this button

But it's only visible when you select a single graphical lump. If you want to do a mass-recolor, you can select multiple graphics and then use context menu from right-click.

Now let's look at recolor menu:

Origin range (1) is the colors of the original sprites you want change. You can select a single color or an continuous row of them - typically you will select all the shades of the same color, baron's red torso, for example, is entirely second half of the first row and first half of the second row.

Target range (2) is what we want our new image to have instead. The range doesn't have to be the same length, it will translate proportionately.

Translation ranges (3) is the list of all changes you will want to do at once. It's important to do if you want to swap colors - in our case as we are going to make baron's torso green, it will be the same color as his fists's glow. Plus sign lets you add a new entry, minus sign removes current entry. The arrows change the order of execution, but I can't imagine when would it matter.

Preview (4) shows you the graphics, as it will end up looking. You can also point your mouse at it to see color highlighted on Resulting Palette (5) to give you a hint what exactly the colors are. It's not very convenient though because pixels are so small.

So, let's start translating, shall we?

We have selected the destaturated red range as origin, and green range as target and got ourself our juicy hell orc. But we don't want his hands to glow the same shade, do we? Let's make the glow yellow

Yellow is an awkward color because the yellow range is split in two - but it goes to show that we can select a partial range just as well. Some ranges are mismatched in saturation (For example, green doesn't have the same fade to white as blue, yellow or red) so you might want to change target range or limit the original range to manipulate the proportions. This is something you'll have to do yourself, depending on how you want your graphics to look.

Now let's check all the sprites to make sure nothing got miscolored.

Uh-oh, we forgot that Baron's blood was green, and now it looks like our new baron was filled with urine. Gross.

That shows the limitation of the tool - it can only edit the whole picture. We'll have to use a more advanced editor, like Paint.NET or GIMP to do more complex edits. Luckily, we can still benefit from the job SLADE done for us with this translation. For example by making the version of our hell orc that doesn't recolor green into anything, exporting, overlapping the two sprites in graphical editor and erasing the miscolored parts.

Naturally, this technique works best on relatively monochrome art, like a brick texture than it does on monsters.