myImageIO.h

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>

class myImageData{

private:
	int mW;
	int mH;
	int mCH;
	double * mData;
	
	void SkipComments(FILE *fp){
		int ch;
    	char line[100];
 
    	while ((ch = fgetc(fp)) != EOF && isspace(ch))
        	;
    
    	if (ch == '#') {
        	fgets(line, sizeof(line), fp);
        	SkipComments(fp);
	    }else{
	        fseek(fp, -1, SEEK_CUR);
		}
	}

public:

	myImageData(void){
		this->mData = NULL;
	};

	~myImageData(){ 
		if(this->mData != NULL){
			delete [] this->mData;
		}
	}

	void init(int W, int H, int CH){
		this->mW = W;
		this->mH = H;
		this->mCH = CH;
		if(this->mData != NULL) delete [] this->mData;
		this->mData = new double[(this->mW)*(this->mH)*(this->mCH)];
	}
	
	int getWidth(void){ 
		return this->mW;
	}
	
	int getHeight(void){ 
		return this->mH;
	}
	
	int getCH(void){ 
		return this->mCH;
	}

	double * getDataPtr(void){ 
		return this->mData;
	}

	double get(int x, int y){
		return this->mData[y*(this->mW) + x];
	}
	
	double get(int x, int y, int CH){
		return this->mData[this->mCH * ( y*(this->mW) + x) + CH];
	}
	
	void set(int x, int y, double value){
		this->mData[y*(this->mW) + x] = value;
	}
	
	void set(int x, int y, int CH, double value){
		this->mData[this->mCH *(y*(this->mW) + x) + CH] = value;
	}

	void read(const char *filename);	
	void save(const char *filename);
	
};


void myImageData::read(const char *filename){
	
	FILE *file = fopen(filename, "rb");
	if(file == NULL){
		printf("Cannot open %s\n", filename);
		exit(1); //abnormal termination
	}
	printf("Read an image from: %s\n", filename);
	
	// read ppm/pgm header
	
	char buf[256];
	char filetype[256];
	int W, H, Range, CH;
	
	fgets(buf, sizeof(buf), file);
	sscanf(buf, "%s", filetype);
	
	SkipComments(file);
	fgets(buf, sizeof(buf), file);
	sscanf(buf, "%d%d", &W, &H);
	
	SkipComments(file);
	fgets(buf, sizeof(buf), file);
	sscanf(buf, "%d", &Range);
	//printf("Header: %s, %d, %d, %d\n", filetype, W, H, Range);
	
	SkipComments(file);
	
	if(strcmp(filetype, "P5") == 0){
		CH = 1;
	}else if(strcmp(filetype, "P6") == 0){
		CH = 3;
	}else{
		printf("Unknown image type\n");
		exit(1); //abnormal termination
	}
	
	if(Range != 255){
		printf("Invalid data\n");
		exit(1); //abnormal termination
	}
	
	// create myImageData class
	
	init(W, H, CH);
	
	// read ppm data
	
	int datalength = this->mW * this->mH * this->mCH;
	unsigned char * temp = new unsigned char [datalength];
	fread(temp, sizeof(unsigned char), datalength, file);
	
	double * ptr1 = this->mData;
	unsigned char *ptr2 = temp;
	
	for(int i = 0; i < datalength; i++){
		*ptr1 = (double)*ptr2;
		ptr1++;
		ptr2++;
	}
	
	delete [] temp;

	fclose(file);
	
}

void myImageData::save(const char *filename){
	
	char filenamefull[256];
	if(this->mCH == 1){
		sprintf(filenamefull, "%s.pgm", filename);
	}else{
		sprintf(filenamefull, "%s.ppm", filename);
	}

	FILE *file = fopen(filenamefull, "wb");
	printf("Write an image to: %s \n", filenamefull);
	
	if(this->mCH == 1){
		fprintf(file, "P5\n");
	}else{
		fprintf(file, "P6\n");
	}
	
	fprintf(file, "%d %d\n", this->mW, this->mH);
	fprintf(file, "255\n");
	
	int datalength = this->mW * this->mH * this->mCH;
	unsigned char * temp = new unsigned char [datalength];
	
	double * ptr1 = this->mData;
	unsigned char * ptr2 = temp;
	
	for(int i = 0; i < datalength; i++){
		double value = *ptr1;
		value = round(value);
		if(value > 255) value = 255;
		if(value < 0) value = 0;
		*ptr2 = (unsigned char)value;	
		ptr1++;
		ptr2++;
	}	
	
	fwrite(temp, sizeof(unsigned char), datalength, file);
	delete [] temp;
	
	//fprintf(file, "\n");
	
	fclose(file);
}