Detecting Colors with the SparkFun Tristimulus Color Sensor

2024-10-31 | By SparkFun Electronics

License: See Original Project Light Arduino

Guide by KJB

Introduction

In this tutorial, we'll show you how to use the SparkFun Tristimulus Color Sensor - OPT4048DTSR ‎‎(Qwiic) to detect and classify colors based on their CIE XYZ color space values. The sensor is ‎capable of measuring the color intensity in the X, Y, and Z channels, which correspond to red, ‎green, and blue components in a simplified form.‎

If you are looking for the full Hookup Guide for the SparkFun Tristimulus Color Sensor - ‎OPT4048DTSR (Qwiic), click the button bellow. This guide only covers a simple project to get you ‎started quickly, while the full Hookup Guide goes over every detail of the sensor.‎

VIEW THE FULL HOOKUP GUIDE

‎Hardware Needed

To follow this experiment, you will need the following materials. While this is a simple project, we ‎wanted to make sure that you have everything you need to get started before we get to the code. ‎For this simple project we chose the RedBoard Qwiic but you could choose from many of our ‎development boards such as the Qwiic Pro Micro as well.‎

‎Software Setup

Note: If this is your first time using Arduino, please review our tutorial on installing the Arduino ‎IDE. If you have not previously installed an Arduino library, please check out our installation guide.‎

Installing the Required Libraries

Install the SparkFun OPT4048 Library: Open the Arduino IDE and navigate to Sketch > ‎Include Library > Manage Libraries. In the Library Manager, search for "OPT4048" and ‎install the latest version from SparkFun.‎

Read Measurements with a Serial Monitor

Now that we've installed the Arduino library, it's time to upload our first sketch to make sure ‎everything is working properly, and you are able to read basic measurements with your Serial ‎Monitor in the Arduino IDE.‎

For this example you will need the SparkFun Tristimulus Color Sensor - OPT4048DTSR (Qwiic), ‎a SparkFun RedBoard Qwiic, a Qwiic Cable, and a USB Micro-B Cable.‎

Using the Qwiic system, assembling the hardware is simple. Connect the RedBoard to one of the ‎SparkFun Tristimulus Color Sensor Qwiic ports using your Qwiic cables (please remember to insert ‎this cable in the correct orientation). Then connect the RedBoard to your computer via the ‎MicroUSB cable and voila! You're ready to rock!‎

redboard_1

SparkFun Tristimulus Color Sensor to RedBoard

‎ Alternatively, you can copy and paste the code below into a shiny new Arduino sketch:‎

Copy Code

#include "SparkFun_OPT4048.h"  // Include the SparkFun OPT4048 library
#include <Wire.h>  // Include the Wire library for I2C communication

SparkFun_OPT4048 colorSensor;  // Create an instance of the OPT4048 color sensor

void setup() {
 Serial.begin(115200);  // Initialize serial communication at 115200 baud
 Serial.println("OPT4048 Color Sensing Example");  // Print a message to the serial monitor

 Wire.begin();  // Initialize the I2C bus

 if (!colorSensor.begin()) {  // Try to initialize the color sensor
   Serial.println("OPT4048 not detected - check wiring or I2C address!"); 
   while (1);  // Enter an infinite loop to halt the program
 }

 colorSensor.setBasicSetup();  // Apply basic setup configuration to the sensor

 Serial.println("Sensor initialized and ready!");  // Print a success message
}

void loop() {
  float x = colorSensor.getCIEx();  // Get the CIE X value from the sensor
  float y = colorSensor.getCIEy();  // Get the CIE Y value from the sensor
  float z = 1 - x - y;  // Approximate the CIE Z value (this is a simplification)

  Serial.print("CIEx: ");  // Print label for CIE X value
  Serial.print(x, 4);  // Print CIE X value with 4 decimal places
  Serial.print(" CIEy: ");  // Print label for CIE Y value
  Serial.print(y, 4);  // Print CIE Y value with 4 decimal places
  Serial.print(" CIEz: ");  // Print label for CIE Z value
  Serial.print(z, 4);  // Print approximated CIE Z value with 4 decimal places

  String detectedColor = classifyColor(x, y, z);  // Classify the color based on CIE values
  Serial.print(" Detected color: ");  // Print label for detected color
  Serial.println(detectedColor);  // Print the classified color

  delay(600);  // Wait for 600ms before the next reading (3 channels * 200ms conversion time)
}

String classifyColor(float x, float y, float z) {
  float total = x + y + z;  // Calculate the sum of x, y, and z
  float r = x / total;  // Calculate the relative red component
  float g = y / total;  // Calculate the relative green component
  float b = z / total;  // Calculate the relative blue component

  // The following if statements check the RGB ratios to classify the color
  if (r > 0.4 && g < 0.3 && b < 0.3) return "Red";
  if (r < 0.3 && g > 0.4 && b < 0.3) return "Green";
  if (r < 0.3 && g < 0.3 && b > 0.4) return "Blue";
  if (r > 0.3 && g > 0.3 && b < 0.3) return "Yellow";
  if (r > 0.3 && g < 0.3 && b > 0.3) return "Purple";
  if (r < 0.3 && g > 0.3 && b > 0.3) return "Cyan";
  if (r > 0.3 && g > 0.3 && b > 0.3) return "White";
  if (r < 0.1 && g < 0.1 && b < 0.1) return "Black";

  return "Unknown";  // If no color matches, return "Unknown"
}

Make sure you've selected the correct board and port in the Tools menu and then hit the upload ‎button. Once the code has finished uploading, go ahead and open a Serial Monitor. Set the baud ‎rate to 115200. You should see output like this:‎

output_2

Interpreting the Results

CIEx, CIEy, CIEz: These are the values from the CIE 1931 color space which represent the ‎color's chromaticity.‎
Detected Color: Based on the values, the code attempts to classify the color into a basic ‎category like "Red," "Green," "Blue," etc.‎

The CIEx and CIEy values are going to fall somewhere between 0 and 1. Page 35 of ‎the datasheet gives more detail on this, but generally speaking, you can map the predominant color ‎of the space you're measuring using the following:‎

plots_3

plots_4

CIE XY and CIE UV space plots of color coordinates

For more information on the CIE and CIY values, refer to the CIE 1931 Color Space Wiki Page.‎

If you see unexpected values or the sensor isn’t detected, double-check your wiring and ensure ‎the sensor is properly connected to the I2C bus.‎

Conclusion

You've successfully set up the SparkFun Tristimulus Color Sensor to classify colors based on CIE ‎XYZ values. This tutorial provides a foundation for more advanced color detection projects. You can ‎now expand on this knowledge to create sophisticated color analysis systems or integrate the ‎sensor into larger, more complex projects.