Add color section to the troubleshooting document

mipidsi/docs/TROUBLESHOOTING.md

@@ -9,3 +9,47 @@ This driver does **NOT** handle the backlight pin to keep the code simpler. User
 ### Transport misconfiguration (e.g. SPI)
 
 Make sure that the transport layer is configured correctly. Typical mistakes are the use of wrong SPI MODE or too fast transfer speeds that are not supported by the display
+
+## Incorrect colors
+
+The way colors are displayed depend on the subpixel layout and technology (like TN or IPS) used by the LCD panel. These physical parameters aren't known by the display controller and must be manually set by the user as `Builder` settings when the display is initialized.
+
+To make it easier to identify the correct settings the `mipidsi` crate provides a `TestImage`, which can be used to verify the color settings and adjust them in case they are incorrect.
+
+```rust
+let mut display = Builder::ili9486_rgb666(di)
+    .init(&mut delay, Some(rst))?;
+
+TestImage::new().draw(&mut display)?;
+```
+
+The expected output from drawing the test image is:
+
+![Correct colors](colors_correct.svg)
+
+If the test image isn't displayed as expected use one of the reference image below the determine which settings need to be added to the `Builder`.
+
+### Wrong subpixel order
+
+![Wrong subpixel order](colors_wrong_subpixel_order.svg)
+
+```rust
+.with_color_order(mipidsi::options::ColorOrder::Bgr)
+```
+
+### Wrong color inversion
+
+![Wrong color inversion](colors_wrong_color_inversion.svg)
+
+```rust
+.with_invert_colors(mipidsi::options::ColorInversion::Inverted)
+```
+
+### Wrong subpixel order and color inversion
+
+![Wrong subpixel order and color inversion](colors_both_wrong.svg)
+
+```rust
+.with_color_order(mipidsi::options::ColorOrder::Bgr)
+.with_invert_colors(mipidsi::options::ColorInversion::Inverted)
+```