Basic python scripts that modify the color patch files in Gran Turismo 4, which allow for custom colors on certain cars.

Current tooling is crude and unfinished, and requies using multiple separate scripts

Credit goes to Nenkai for file format research and figuring. https://github.com/Nenkai/GT-File-Specifications-Documentation

To do:

• Integrate all scripts into one
• Add more images for usage instructions

Bringing back the Pink Vitz:

Adding the infamous Y49 Barbados Yellow to the 1990 CR-X:

Adding the 1996 DX and CX exclusive Midori Green Pearl to the '97 Civic Type R:

Adding new vibrant colors to the SLR Mclaren:

Adding missing factory colors to the '95 Eclipse:

Adding the 1996 Exclusive Blue with white stripes to the '99 Viper GTS:

Adding a solid white Toyota TS020:

How to use:

1. Extract the .pat file from the Menu model and save to a separate file. It's recommended to create a new folder to hold the assets for the particular car you're going to work on. Name it the model code (hond0008 for example), and create it in the same directory as your car/menu folder in your host filesystem. Create a shortcut file to the menu model file, and one to the lod model .pat file and add both of these shortcuts to your folder to make the UI navigation easier.

Using the model extractor & rebuilder script, click "Extract model" and find your model file. Then, select the desired assets to extract from the model. For this, you would only need to select the MainModelColorPatch, and maybe the WheelColorPatch if that particular car has multiple wheel colors and you want to add extra wheel colors. Examples of these are: 'integra_r_03' (hond0036) and '_5_turbo_80' (re__0003). Save the files to your folder, then proceed to modify the color patch file.

2. Using the color adder script, add additional color entries to the pat file and save. Do this for both the menu pat, and the lod/open pat.

3. Next, open the color editor script. Select one of the paint tabs, and export it to a PNG. You will want to also export a different paint as well, so that you can compare the difference between them, so that you will know which pixels to modify. When choosing which color to use for determining which pixels are the right ones, it's best to compare two colors that are not shades. For example, green and blue.

4. Open the PNGs in an image editor, and splice the strips together. Pick one of strips to modify. Use the color picker tool to check the difference between the pixels on each strip. Looking at the V in the HSV will make it obvious if a pixel is different (thus a relevant pixel) versus the same (not relevant). Take the selection tool on add mode, and select each relevant pixel in the strip. Alternate between the color picker and selection tool until all relevant pixels are selected. Some cars will have color patches with byte-shifted target offsets, missing target offsets, and incomplete patch sizes. Remember, we are technically editing bytes directly, not actual pixels necessarily. In these cases, you'll have to do various things to fix these issues. For incomplete patch sizes, this will cause certain spots on the car to not change color fully. Typically this is seen as a patch size that doesn't cover the full 4 bytes for a certain color, so the remaining 1-3 bytes don't get patched. As seen on the Eclipse, there was a section within the front grille that would stay red despite adding green and blue color values to the pixel. Manual hex editing of the pat file is required to adjust patch sizes currently. For missing target offsets, this will prevent you from editing certain things about the paint, like materials. This is common on cars with low color counts, as the original color options might not have different material parameters, so the color patch won't include the bytes necessary to change it. Manual hex editing of the pat file is required to add / change target offsets currently. For byte-shifted offsets, this will cause certain pixels in the PNG strip to be mis-aligned and make it difficult to know what the actual color data should be. In my limited work of the cars I have done, this has only happened with the Toyota TS020, and should be quite rare. You can inspect the bytes being patched and try to correct the target offsets in question, or you can simply deduce which pixels are mis-aligned through trial and error, and then set the Red, green, blue, and opacity values accordingly, which is equally as tedious as adjusting the target offsets.

Once they are all selected, apply your desired adjustments/effects. Really though, the only practical adjustment is the Hue. The best way to modify the hue is to use the levels tool (paint.net) or equivalent. Find the brightest, most opaque, and most saturated pixel in the strip, and use the color values from it as the input values in the levels tool. Then, set the output values in the levels tool to a desired color. For example, you can look up a manufacturer paint code and convert it to an approximated RGB value to use here. Other effects and adjustments to the pixels will likely mess up the shading, so be mindful. The most obvious sign of poor editing is the door handle area of the car. Once the strip is modified, get rid of the comparison strip and then save the new png. Before closing the image editor, it would also be wise to separately save a 'selection layer' that marks every pixel that needs to be edited.

6. Go back to the color editor, and import your PNG strip into whichever paint tab you want to overwrite, then save. This should be the new one that you added in the previous step, but you can also edit existing colors in the patch as well if you want to.

7. Repeat this process for each pat file the car has, the menu pat(s) and the lod/open pat(s). Also, menu pats and lod/open pats have different data sizes, so you can't use the same PNG strip for both. You will want to take note of the exact hue shift settings / effects you applied to the first one, then apply the same exact settings to the other, to get consistent results between the menu model and lod/open model.

8. Update the menu model with the new pat file(s). Go back to the the model extractor & rebuilder script to overwrite the new menu pat file(s) into the menu model.

9. With your new Menu model and new lod/open patch file, simply overwrite the original file(s) with the new ones.

To register the new paint color into the game, update the spec database's VARIATION[region] table and add a new entry for the car, making sure to at least update the VarOrder cell, but also the swatch color settings. To set the swatch color, take your RGB values and convert them to hexadacimal.

For example: 248,185,21 = F8B915 The format of the swatch setting: Unknown value (1 digit), blue, green, red For this paint code, we can use 5 | 15 | B9 | F8, or 515B9F8. Convert that back into a decimal value and input it into the spec database. 515B9F8 = 85309944