Writing Images
FILE* F = fopen( "myImage.raw", "w" );       // on Macs, use "../../../myImage.raw"
if ( F == NULL )
{
		printf("couldn't open file to write\n");
		exit(0);
}
	
fwrite( myImage, width*height, 1, F );
fclose( F );



Reading Images
FILE* F = fopen( "myImage.raw", "r" );        // on Macs, use "../../../myImage.raw"
if ( F == NULL )
{
		printf("couldn't open file to read\n");
		exit(0);
}
	
fread( myImage, width*height, 1, F );
fclose( F );



Warning: Only set pixels within your image bounds
if ( x < 0 || x >- imageWidth || y < 0 || y >= imageHeight )
	continue;													// continue to next loop of for loop


Efficient brush application
for( int y=mouseY-rad; y<=mouseY+rad; y++ )			// limiting for loop to brush region
{
	for( int x=mouseX-rad; x<=mouseX+rad; x++ )
	{
		// blending code (to blend brush paint with existing pixels
		int existingPixel = myImage[ index  ];
		int newPixel = the brush color;
		float p = computed using brush falloff function;

		// linear interpolation (LERP) between old and new pixel values
		myImage[ index  ] = newPixel*(1.0-p) + existingPixel*p;
	}
}