image scaling with C
- by sa125
Hi - I'm trying to read an image file and scale it by multiplying each byte by a scale its pixel levels by some absolute factor. I'm not sure I'm doing it right, though -
void scale_file(char *infile, char *outfile, float scale)
{
// open files for reading
FILE *infile_p = fopen(infile, 'r');
FILE *outfile_p = fopen(outfile, 'w');
// init data holders
char *data;
char *scaled_data;
// read each byte, scale and write back
while ( fread(&data, 1, 1, infile_p) != EOF )
{
*scaled_data = (*data) * scale;
fwrite(&scaled_data, 1, 1, outfile);
}
// close files
fclose(infile_p);
fclose(outfile_p);
}
What gets me is how to do each byte multiplication (scale is 0-1.0 float) - I'm pretty sure I'm either reading it wrong or missing something big. Also, data is assumed to be unsigned (0-255). Please don't judge my poor code :)
thanks
