Incohérent "y + JpegDec.MCUHeight * mcuY" with code

[Barrois]

Here is my code

// https://www.deviceplus.com/arduino/jpeg-decoding-on-arduino-tutorial/ // Include the library

include

include // SPIFFS

// this function determines the minimum of two numbers

define minimum(a,b) (((a) < (b)) ? (a) : (b))

// The coordinate variables int x, y, mcuX, mcuY; // The color of the current pixel int inColor, r, g, b; unsigned int s_s_x, s_s_y; // sauve les coordonnées du point noir unsigned int tableau[32]; // deux fois 4 x 4 unsigned int quelle_carre , carre_1, carre_2; unsigned int x_noir, y_noir, noir ; void setup() {

// Begin Serial port for communication with PC Serial.begin(115200); Serial.println(FILE);
Serial.println(".........................init");

//Initialize SPIFFS

Serial.println("Initializing SPIFFS... "); SPIFFS.begin(); if(!SPIFFS.begin()){ Serial.println("SPIFFS Mount Failed"); return; } char NOM_jpg[] = "/Image7.jpg"; Serial.printf("Picture file name: %s\n", NOM_jpg);

File jpgFile = SPIFFS.open(NOM_jpg,"r");
if(!jpgFile){
// File not found 
Serial.println("Failed SPIFFS to open file");
return;

} Serial.println("...................open....JPGFILE"); if(!jpgFile){ Serial.println("Failed to open jpgFile"); } // Decode the JPEG file JpegDec.decodeSdFile(jpgFile); //................ l'image est decodée

Serial.print(".............image decodee : ");
Serial.print( JpegDec.width) ;
Serial.print(" x ") ;
Serial.print("Height    :");
Serial.println(JpegDec.height);
Serial.print("Components:");
Serial.println(JpegDec.comps);
Serial.print("MCU / row :");
Serial.println(JpegDec.MCUSPerRow);
Serial.print("MCU / col :");
Serial.println(JpegDec.MCUSPerCol);
Serial.print("Scan type :");
Serial.println(JpegDec.scanType);
Serial.print("MCU width :");
Serial.println(JpegDec.MCUWidth);
Serial.print("MCU height:");
Serial.println(JpegDec.MCUHeight);
Serial.println("");    

 // Create a buffer for the packet
char dataBuff[240];

// Fill the buffer with zeros
initBuff(dataBuff);

// Pointer to the current pixel
uint16_t *pImg;      
// Color of the current pixel
uint16_t color;    

    // Repeat for all MCUs in the image...............
while(JpegDec.read()) {
      Serial.print(".............MCU : ");
      Serial.println(JpegDec.read());          
  // Save pointer the current pixel
  pImg = JpegDec.pImage;

  // Get the number of pixels in the current MCU
  uint32_t mcuPixels = JpegDec.MCUWidth * JpegDec.MCUHeight;
      Serial.print(".................mcuPixels : ");
      Serial.println(mcuPixels);    
  // Repeat for all pixels in the current MCU
  while(mcuPixels--) {
    // Read the color of the pixel as 16-bit integer
    color = *pImg++;

  // Convert 16-bit color into RGB values
  r = ((color & 0xF800) >> 11) * 8;
  g = ((color & 0x07E0) >> 5) * 4;
  b = ((color & 0x001F) >> 0) * 8;

// https://onlinejpgtools.com/convert-jpg-to-grayscale // 0.21 r + 0.72 b + 0.07 v Méthode BT-709

  int s_gris = 0.21 * r + 0.72* b +0.07 * g; // nuance de gris
    s_s_x = x + JpegDec.MCUWidth*mcuX ;      // on garde les coordonnées
    s_s_y = y + JpegDec.MCUHeight*mcuY;      //  s_s_x et s_s_y 

tableau[s_s_x,s_s_y] = s_gris ;

// Serial.print("+++++++++++++ point le plus noir est en : "); Serial.print(s_s_x); Serial.print(" , "); // if (s_s_y > 2640 ) s_s_y = s_s_y - 2640; // ????? du à la copie Serial.print(s_s_y); // Serial.print(" et sa couleur est : "); Serial.print(" , ");
Serial.println (s_gris);
// } // }

  // Move onto the next pixel
  x++;

  if(x == JpegDec.MCUWidth) {
    // MCU row is complete, move onto the next one
    x = 0;
    y++;
  }

  if(y == JpegDec.MCUHeight) {
    // MCU is complete, move onto the next one
    x = 0;
    y = 0;
    mcuX++;
  }

  if(mcuX == JpegDec.MCUSPerRow) {
    // Line of MCUs is complete, move onto the next one
    x = 0;
    y = 0;
    mcuX = 0;
    mcuY++;
  }

  if(mcuY == JpegDec.MCUSPerCol) {
    // The entire image is complete
    return;
  }
}

} }

// Function to fill the packet buffer with zeros void initBuff(char* buff) { for(int i = 0; i < 240; i++) { buff[i] = 0; } }

void loop() { // Nothing here // We don't need to send the same images over and over again } int getMin(int* array, int size){ int minIndex = 0; int min = array[minIndex]; for (int i=1; i<size; i++){ // if (min<array[i]){ // What you wrote if (array[i] < min){ // What Rob wrote minIndex = i; min = array[i]; } } return minIndex; }

[Bodmer]

It looks like you do not initialise the variables correctly so they are undefined initially... use:

int x = 0, y = 0, mcuX = 0, mcuY = 0;

[Barrois]

Yes ! You are right ! in fact it is in the definition of the table, which has nothing to do ... Thanks a lot for your help.