2d array from external file

[calvarado777]

Hello all! After many hours...and days...I think I finally understand a hw problem. However I am having two issues..one is minor.

Assignment: treat an image file as a quad (2d array) and then break up the array into quads, determine the average color of the quad and the variance, then depending on whether we are at a single pixel or the variance is below a threshold, write the entire quad or pixel with the average.
Write the final compressed array to a new pgma file.

1st minor problem:
When I am first creating a 2d array from my pgma file, I am somehow missing the 1st important element that I need-- I am assuming that it never actually gets written to the array?

2nd huge problem... when I uncomment my compressImage function, I end up in an infinite loop and I start outputting data to the console, and never actually write a compressed image file...can anyone please help?

#include <cstdlib>
#include <iostream>
#include <fstream>
#include <string>

int imageMatrix [512][512];
int outputMatrix [512][512];

using namespace std;



void compressImage(int x, int y, int width, int height, int threshold)
{
	int sum;                             //when i do make it to this stage it seems like the outputMatrix is getting output to the console and gets stuck in an infinite loop? 
	int average;
	double temp;
	double variance;
	int i, j, m, n;
	
	for (i = 0; i < width; i++)						
	{
		for (int j = 0; j < height; j++)
		{						
			sum += imageMatrix[i][j];	
		}
	}		
	average = sum/(i*j);											//calculate average
	
	
	for (m = 0; m < width; m++)     //when i introduce this loop it somehow chnages my average
	{
		for (int n = 0; n < height; n++)
		{
			temp = (imageMatrix[m][n] - average) * (imageMatrix[m][n] - average);		
		}
	}	
	variance = temp / ((m * n)-1);									//calculate variance
	
	
	
	if(width == 1 || height == 1)
	{
		outputMatrix[x][y] == imageMatrix[x][y];					//if at single pixel, write pixel to output array
	}
	
	else if(variance <= threshold)
	{
		for(i = 0; i < width; i++)								// if quad variance is < threshold, write whole quad to output array
		{
			for (j = 0; j < height; j++) {
				outputMatrix[i][j] = average;
			}
		}
	}
	else
	{
		compressImage(x, y, width/2, height/2, threshold);
		compressImage(x + (width/2), y, width - (width/2), height/2, threshold);
		compressImage( x + (width/2), y + height/2, width - width/2 , height - height/2, threshold); 
		compressImage(x, y + height/2, width/2, height - height/2, threshold);
	}
	
	//const char* const OutputFileName = "outputBaboon.pgma";
	ofstream dataOut("outputBaboon.pgma");
	//dataOut.write(outputMatrix);
	//dataOut.close();
	
	
	
	
	for (i = 0; i < width; i++) 
	{
		for (j = 0; j < height; j++) 
		{
			dataOut << outputMatrix[i][j];
		}
	}
	dataOut.close();
	 
	
}


int main (int argc, char * const argv[]) {
	
	const char* const FileName = ("/Users/seanmacbook/Desktop/ClaudiaSchool/Multimedia/Alvarado_Multimedia_Proj1/build/Debug/baboon.pgma");
	std::ifstream dataIn;
	dataIn.open(FileName);
	
	if(!dataIn)
		std::cout << "Can't open file " << FileName;
	else {
		string line;
		string line2;
		string line3;
		string line4;
		int width, height;
		getline(dataIn, line);
		getline(dataIn, line2);
		cout << line;
		cout << line2;
		dataIn >> width;
		cout << width << " ";
		dataIn >> height;
		cout << height << " ";
		getline(dataIn, line3);
		cout << line3 << " ";
		int imageMatrix[width][height];
		

		for (int i = 0; i < width; i++) {             //i think this is one issue
			for (int j = 0; j < height; j++) {
				
				dataIn >> imageMatrix[i][j];
			}
		}	

		for (int i = 0; i < width; i++) {
			for (int j = 1; j < height; j++) {
				
				cout << imageMatrix[i][j];
				cout << " ";
			}			
		}
	
		
		//compressImage(0, 0, width, height, 126);
	}
	
	
    // insert code here...
    cout << "Hello, World!\n";
    return 0;
}

[soranz]

Are you sure that width/2 and height/2 eventually both reach 1 ?

The loop doesn't change average this does:

//each of these variables are integers but the division 
//whenever sum/(i*j) creates a decimal it won't be properly stored into 'average'
average = sum/(i*j);