Arduino GFX vs. Adafruit GFX — Differences in Color Reproduction

[embedded-kiddie]

When the same RGB565 image is displayed on the same LCD device, the color reproduction on that LCD is expected to be identical.

However, the reality seems to be different. With Arduino GFX, the colors appear to be off.

If looking closely at the original image, the top of the panda's head appears slightly pinkish, whereas the Adafruit GFX version looks closer to the original.

So, my question: Is there a way to match the color reproduction?

Thank you.

Sample Image

Original

Adafruit GFX

Arduino GFX

Test environment

H/W

• Board: Arduino UNO R4 WiFi
• LCD: 2.8inch SPI Module ILI9341
  • https://www.lcdwiki.com/2.8inch_SPI_Module_ILI9341_SKU:MSP2807

S/W

• ArduinoCore-renesas: 1.6.0
• Arduino GFX: 1.6.9
• Adafruit GFX: 1.12.6

Sketch

#include <Arduino.h>
#include <SPI.h>
#include "panda.h"

#define TFT_BLACK 0x0000

// GPIO pin assignment
#define TFT_RST       D8    //  8
#define TFT_DC        D9    //  9
#define TFT_CS        CS    // 10
#define TFT_MOSI      MOSI  // 11
#define TFT_MISO      MISO  // 12
#define TFT_SCLK      SCK   // 13
#define TFT_BL        -1    // Connect directly to 3.3V
#define SPI_FREQUENCY 24000000 // The maximum is 24MHz for UNO R4 (4MHz is relatively stable)

#if   false
//--------------------------------------------------------------------------------
// Adafruit GFX
//--------------------------------------------------------------------------------
  #include <Adafruit_ILI9341.h>
  #define GFX(f)    tft.f

  Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC);

#else
//--------------------------------------------------------------------------------
// Arduino GFX
//--------------------------------------------------------------------------------
  #include <Arduino_GFX_Library.h>
  #define GFX(f)    tft->f
  #define drawRGBBitmap draw16bitRGBBitmap

  Arduino_DataBus *bus = new Arduino_HWSPI(TFT_DC, TFT_CS);
  Arduino_GFX *tft = new Arduino_ILI9341(bus, TFT_RST);
#endif

void setup() {
  GFX(begin(SPI_FREQUENCY));
  GFX(fillScreen(TFT_BLACK));
  GFX(setRotation(0));

  GFX(drawRGBBitmap(0, 0, panda, PANDA_WIDTH, PANDA_HEIGHT));
}

void loop() {}

RGB565 data

panda.h.zip

panda.h was created using https://notisrac.github.io/FileToCArray/ from the original image as follows:

[moononournation]

Arduino_ILI9341 actually have 3 type init instruction sets defined, default using ili9341_type1_init_operations. you may try replace the code

Arduino_GFX *tft = new Arduino_ILI9341(bus, TFT_RST);

with

Arduino_GFX *tft = new Arduino_ILI9341(
  bus, TFT_RST, 0 /* rotation */, false /* ips */, ILI9341_TFTWIDTH, ILI9341_TFTHEIGHT,
  bus, TFT_RST, 0 /* rotation */, true /* IPS */, 240 /* width */, 320 /* height */,
  52 /* col offset 1 */, 40 /* row offset 1 */, 53 /* col offset 2 */, 40 /* row offset 2 */,
  ili9341_type2_init_operations, sizeof(ili9341_type2_init_operations)
);

or ili9341_type3_init_operations to check the effect.

[embedded-kiddie]

Hi @moononournation ,

Thank you for the solution. Here is the quick reports.

type2

Arduino_GFX *tft = new Arduino_ILI9341(
  bus, TFT_RST, 0 /* rotation */, false /* ips */, ILI9341_TFTWIDTH, ILI9341_TFTHEIGHT,
  52 /* col offset 1 */, 40 /* row offset 1 */, 53 /* col offset 2 */, 40 /* row offset 2 */,
  ili9341_type2_init_operations, sizeof(ili9341_type2_init_operations)
);

type2 (offset = 0)

Arduino_GFX *tft = new Arduino_ILI9341(
  bus, TFT_RST, 0 /* rotation */, false /* ips */, ILI9341_TFTWIDTH, ILI9341_TFTHEIGHT,
   0 /* col offset 1 */,  0 /* row offset 1 */,  0 /* col offset 2 */,  0 /* row offset 2 */,
  ili9341_type2_init_operations, sizeof(ili9341_type2_init_operations)
);

type3

Arduino_GFX *tft = new Arduino_ILI9341(
  bus, TFT_RST, 0 /* rotation */, false /* ips */, ILI9341_TFTWIDTH, ILI9341_TFTHEIGHT,
   0 /* col offset 1 */,  0 /* row offset 1 */,  0 /* col offset 2 */,  0 /* row offset 2 */,
  ili9341_type3_init_operations, sizeof(ili9341_type3_init_operations)
);

The issue was also resolved using the 2.4-inch 8-bit parallel ILI9341 (https://www.lcdwiki.com/2.4inch_Arduino_Display) with the UNO R4 and CYD!

It is very helpful that you support so many variants of the ILI9341.
Thank you again!!

[embedded-kiddie]

Sorry, but I had only searched within the "Discussions" section regarding my question.
Upon searching the "Issues" section again, I found #744, which provides a solution.