Requires:
- Basic Resourcepack Knowledge
- Paint.NET

[IF YOUR TEXTURE IS ALREADY AFFECTED BY COLORMAPS, SKIP TO STEP 1!]

Step 0.1: Load your texture into Paint.NET

Step 0.2: Create a new layer

Step 0.3 Import a vanilla grey texture that is affected by colormaps

Step 0.4 Use the Hue / Saturation tool (CTRL + SHIFT + U) to change the color pallete of your texture to be as close to the vanilla texture as possible.
(You can do this by comparing the darkest/lightest pixel in your texture and trying to match the darkest/lightest pixel in the vanilla texture.)

Step 1: Set the brightness to 90, and the contrast to 20 using the Brightness / Contrast Tool (CTRL + SHIFT + T)

Step 2: Open the color picker, and set the color to 00FFFF

Step 3: Select the magic wand tool, and shift-click the transparent pixels on the image. (If you don't have transparent pixels, just select the entire thing)

Step 4: Invert the selection. (CTRL + I)

Step 5: Copy it (CTRL + C)

Step 6: Make a new layer

Step 7: Paste it (CTRL + V)

Step 8: Fill the selection with the light blue color (BACKSPACE)

Step 9: Select the wrench (Properties) in the layers box.

Step 10: Set the blend type to lighten and opacity to 100

Step 11: Combine all layers and then save.